Thursday, October 12, 2006

XP - SiS PCI to USB Enhanced Host Controller - Unknown Device - Simple Things First!


No, sorry, I don't have the hotfix. When it didn't work for me I un-installed it and trashed the download.

It really wasn't much trouble at all to get the hotfix from Microsoft. I just called them on the phone, gave them the KB article number and explained that the KB article said to contact them for the hotfix. Then I got transferred to someone who made sure I knew what I was talking about, and that I understood the hotifx might not work and had not gone through all the testing. This second person then sent me the link and a time-limited password to open the file via email.

You did try unplugging everything for half an hour and holding in the power button for a minute, didn't you? ;>) I'm still mad at myself for not trying that first.]


If your XP computer's integrated USB hardware stops working, try shutting it down and disconnecting it from the power source for half an hour.

Long version:

The integrated USB2 hardware on my confuter's motherboard quit working.

The machine is a three or four year old 1.6 GHz Pentium 4 running Windows XP Home SP2. The motherboard itself (Gigabyte RZ Series, 8S651MP-RZ) is newer, having replaced the one whose cazapitors blew a year or two ago. The machine is kept up to date with OS patches, and is as well protected from creepware as I can make it. It's also reasonably well protected from power glitches.

Nothing lasts forever, but there wasn't any reason for the USB to have quit working. What might have precipitated the problem was installation of the APC PowerChute Personal Edition software that came with my new APC UPS, and connection of the new UPS's comm port to one of the ports on a powered USB hub connected, in turn, to one of the computer's USB ports. The APC software is supposed to allow the UPS to shut down the computer if there's a power outage of a given duration. I didn't test that function while things were still working, but if I re-install the UPS software and reconnect the UPS to the computer, I will certainly test it. For now, though, I'm a bit hesitant.

I became obsessed with fixing the motherboard's integrated USB hardware, and probably spent more time on it than I should have. At first I was pretty happy because a bit of googling pointed to the "SiS PCI to USB Enhanced Host Controller" part of the USB setup in the Device Manager*. Following the suggestion, I disabled the "SiS PCI to USB Enhanced Host Controller" in the Device Manager and, like magic, USB started working again. That being the case, I started an incremental backup to my USB hard drive before I went to bed.

(*You can get to the Device Manager through Properties on My Computer, or by hitting the Windows and Pause/Break keys on the keyboard at the same time.)

In the morning I was surprised to find that my incremental backup was still running. That led to the realization that what I had actually done was to disable the faster USB2 while reviving the glacial USB1 functions. Better than nothing, but unacceptable. Back to Google.

I was reasonably certain there was nothing wrong with my hardware since the USB still worked under version 1, so I carried out different suggested remedies such as obtaining the latest drivers, removing the USB entries in the Device Manager and re-booting and so on, most of which I'd already tried.

One authoritative-sounding suggestion was to simply give up early and install a USB card instead of wasting time trying to fix the integrated USB.

I tried a few things I thought might help, like disabling USB support in the BIOS and then running my registry fixer program immediately after rebooting. RegSupreme Pro found a lot of stuff to toss, but this did not solve the USB problem. Nothing I did solved the USB problem. The Microsoft web site was not helpful at all when I went looking for USB-related help (or maybe I didn't look hard enough). My motherboard manufacturer didn't help either, simply saying something to the effect that due to Microsoft licensing they only made the drivers available on CD.

Eventually I found something referring to a known issue with XP and USB, so I went back to the Microsoft site and searched a little harder, eventually finding an article (892050) acknowledging the known issue and mentioning a patch file. One would have to contact Microsoft to obtain the patch file, though, apparently because it hadn't gone through all the testing they do. I contacted Microsoft on the phone and in short order had a link in my email inbox to download the patch. I applied the patch to zero effect, and since the problem persisted I uninstalled the patch.

I was about to break down and install a USB card, feeling like an ass for not heeding the earlier advice to give up early on fixing things, but it was already past my bedtime. I remembered the advice to shut down, unplug the machine from the wall, push the power button for one minute and then wait half an hour before firing it up again. I went a little further than that and unplugged all peripherals in addition to the power.

After a minute of holding the power button in, and about 40 minutes of waiting, I came back, plugged everything back in, fired it up and, you got it, it worked like a champ.

Lesson (re)learned: Try the simple things first.


jj mollo said...

Hey, I'm impressed. I personally think that time spent on understanding your tools is not wasted. I like your particular spellings for "confuter" and "cazapitor". I think they're a lot more descriptive that the regulation spellings.

I often tend to feel like an ass when I solve a problem. The answer seems so simpleminded. I must be inadequate in some way. This is really the wrong response, though. We are self-programming to avoid solving problems by beating ourselves up once we solve them. We should rather act like Jack Horner and pat ourselves on the back when we pull out the plum.

Anonymous said...

Steve, Thank you so very much! I have been working on this problem for a week now on a Dell flat panel monitor with a 4 port usb hub that stopped working. Must have happened from a Bill Gates Worked fine for a couple weeks than not recognized anylonger. Tried everything and searched everywhere. Even got Dell Tech support involved they sent me a new monitor, still same problem, I finally figured out on my own to disable the enhanced host controller to get the usb hub recognized, but thanks for the shut down tip, now I have my 2.0 speed also. Thanks Again, John

jerryboy7 said...

Just wanted to say thank you. Your fix worked. Problem started after I plugged in a usb vacuum. I was getting unknown device when I plugged in any usb device(which I knew worked on other pcs).

Anonymous said...

At first I thought: 'This is absurd!' Then I remembered that the way it went unoperative was absurd also and this might actually work! So i did exacly like You wrote and... voila! After few months of sluggish USB 1.1 (I've tried everything that was reasonable and much more that wasn't as well before I gave up for a long time) I have fully operative USB 2.0 again! Huge thanks and best regards from Poland! :)

Anonymous said...

Hi Steve, thanks from a Swede in Japan!

My PC's (ASUS P48SX with SiS 648) USB died completely after it had been working flawlessly for years. No web cam, no USB mouse, no external harddrives etc ...

Microsoft's help was basically to indicate that there is a known problem. If adding and removing USB devices, the system can lock itself and stop recognizing external devices. But their advice to de-install or disable USB related HW and SW and re-install it didn't help at all. Spent hours in the device manager and other utilities.

Making a long story short, yesterday evening I was searching the web for suggestions (and starting to think about buying a new PC) and I got a hit on your blog.

"If your XP computer's integrated USB hardware stops working, try shutting it down and disconnecting it from the power source for half an hour."

I guess I should have thought of it but I didn't. I powered down over night and pressed the power button for well over a minute, and today all USB devices are working again!

Thanks again and best regards from Tokyo!

Alex said...


I am having a nightmare with a USB problem and the hotfix you got from Microsoft would potentially solve it...would you mind sending it to me? I have been unable to get in touch with Microsoft to request a copy from them.

Many thanks in advance,


Steve said...

Sorry, I don't have it. The knowledge base article has phone contact information that might be helpful. When I called them it was fairly painless. Maybe you called at a bad time.

Good luck.

Alex said...

Thanks Steve - found it here in the end:

Mosabsolum said...

OMG That's it! In my case only 5 minutes needed:) Thank you mr. Steve Sturgill.

Anonymous said...

August 2007. I just came across this problem where my daughter's PC locked up when a USB 2.0 device was inserted. Cutting a long story short, YOUR brilliant post solved it. What can I say? Thanks a million mate.

Anonymous said...

Hi!, greetings from Argentina!. Thanks a lot! works fine for me!. This is the most strange and also perfect solution por a hardware problem :s. Thanks again (sorry for my english, i speak spanish) Gracias!


Anonymous said...

Just want to tell you that initially after i read this article, I went back to the google search with the "yeah right" mentality. I cannot believe this actually worked. I can now put pictures from Sept. '07 on my computer, also Thanksgiving, my birthday, X-mas and new years. THANK YOU THANK YOU THANK YOU.....

Vadim said...

Thanks from Russia. It worked fine for me. Just to be clear, was it the Microsoft guy who gave you that advice to shut down etc? Maybe they are not that bad after all?

Steve said...

No, not the Microsoft guy. He was helpful but his advice did not fix the problem.

I'm glad the fix worked for you.

avoidz said...

I'm currently trying to fix this problem on my brother's computer; coincidentally a GIGABYTE 8S661FXMP-RZ.

I'll definitely give the power-down fix a try, since I've tried everything else (including the MS hotfix) to no effect.

Cheers, mate! :)

avoidz said...

You're a lifesaver, it worked :)


Steve said...

Cool! Thanks for the feedback, and Cheers! back at you.


Anonymous said...

Thanks so much for that! You really are a lifesaver - I was about to start looking for something high to jump off!!! :)

Not sure why the power off worked, but it did

Thanks again - I'm raising a virtual glass to ya!


Anonymous said...

Thanks. I had the same problem with an ASROCK motherboard. I was trying to fix it when i came upon your blog.
I Fixed it by doing something much quicker.
You turn off the pc. You unplug the pc from the mains. Then you press the power button (of course the pc doesn't start). Then you can plug the pc to the mains and turn it on. Everything is fixed.

- When you press the power button and there is no power, the system tries to start and consumes every tiny bit of electricity there is inside the pc. It's like you unplug it and wait for some hours.

Steve said...

Steve, I wished I had found this blog about 5 hours ago. My USB ports stopped on Tuesday and I have tried all sorts of things, even uninstalled patches and SP3. This arvo I got out the dreaded CD and booted the PC and reinstalled XP, then SP2 and got all excited as everything worked. Shut down the PC and had tea then booted and saw "Installing USB etc" and all the ports were dead - again. Disabled the controller and everything worked again but got the comment re faster Host. At the moment I'm installing SP3 to see what happens so decided to do a Google with the SIS PCI etc and your lovely advise came up. Once SP3 finishes I will give the PC a finger for a minute and see what happens. Thanks once again.

Anonymous said...

loco sos un ídolo, te besaría las bolas! anduvo joya! mil gracias

Anonymous said...

(Posted from Georgia, USA)
I've been repairing computers for 25 years and this is one of the strangest problems that I've encountered.

I worked on this off and on for over a week. I added and removed devices dozens of times. Many reboots. Many driver reinstalls. I ran sfc/scannow. Twice I restored old registries. I Googled until my Googler was raw. No matter what I did, I couldn't fix this problem until I saw your post. The fix is so simple, yet so conterintuitive. The thing that really through me off is that this computer (which is dual boot) did NOT exhibit the problem under Linux.

In the end, I followed your advice:
1) Disconnect all USB devices
2) Shutdown the computer
3) Unplug the computer
4) Press the power button for 60 seconds
5) Let the computer sit for an hour

After those steps ... the patient was cured! Thank you!!!

Anonymous said...

Thank you very much Steve! I couldn't believe that it works. It did. After a few months I have full speed USB again. Thank you again!

pci compliance said...

his information is very helpful. It really helps me.

Anonymous said...

I had the "Windows XP not recognizing iPod" problem. Followed the advice of "Anonymous from Georgia" and the problem was solved. Info for the impatient: I did not wait 30 mins or an hour as suggested, but immediately turned the PC on again, and things worked fine. Thanks for this simple solution!

devesa from mexico said...

I did it differently, having the pc turned off. without disconnet the usb devices then turned on the voltage regulator and for 1 minute press the power button of the PC will shut down and then turn on normally and all my USB devices were recognized. thanks a lot.

Anonymous said...



JD said...

Wow, July 2011, this still works for a Microsoft XP installation, with Service Pack 3, that has a Linux dual boot system, without Linux having a problem (surely Microsoft should have an updated fix by now!).
Why do we use an Operating System that really doesn't care (about this and creating software with security holes)?
Many thanks Steve,


Anonymous said...

May 2012 and this is what fixed my same issue! Luckily I only spent a day searching for a solution before I ran into this post. Never would have believed this fix was so simple.
Thank you again Steve from another grateful computer owner.

Pedro Faim said...

Thanks so much for that!

Tentei reinstalar drivers e nada funcionou...

Desliguei o computador, tive cerca de 60 segundos a carregar no botão de on/off.
Depois desliguei todos equipamentos de USB e deixei o computador desligado durante a noite.

Hoje liguei o computador e problema resolvido!

Muito obrigado.