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

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[Update:

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.]

Summary:

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.