iPods and Flash Drives Not Recognized by XP SP2

I have a relatively new Compaq desktop with USB 2.0 ports running XP SP2. The entry in the Device Manager is Intel 82801EB USB2 Enhanced Host Controller 24DD.

The problem is whenever I plug in a hard disk-based iPod, an iPod shuffle, or any thumb drive, the Found New Hardware Wizard always comes up. XP cannot find the drivers, I can't find them manually in c:\windows\inf, in the i386 folder, anywhere. Choosing USB mass storage device doesn't work either. I've tried doing Google searches and on driverguide.com for updated drivers, with no luck.

On the iPods, all software is installed and up to date.

On any thumb drive, those don't come with XP drivers.

What I've tried:
1. Deleting all USB entries in the Device Manager in Safe Mode and restarting.
2. Doing #1 and starting up with the device connected.
3. Disabling power management on the USB root hub entries.

I know the hard disk based iPods work because the machine also has FireWire, and they work on that.

However, I'm most concerned about getting the iPod shuffle and the thumb drives working, as they're only USB.

The only other thing I can think of is to uninstall SP2 and try again.

Any other suggestions? This is driving me nuts!

Thanks.