Driver won't load in XP

Hoping someone can help. I've got a USB device that works fine on one
machine with some specific drivers I have. However, when I plug it
into my main PC, XP just will not recognize the driver as belonging to
the device. I've verified that the hardware IDs all show up correctly
and the ones XP shows me are the same as what show in the .inf file.

I've tried everything I can think of (removing the device manually,
deleting all oem*.inf files, removing the usb vid entries in the
registry to let them rebuild, etc.) at this point and can't figure out
what XP has a problem with on it. Any ideas on how to track down the
compatibility issue? Is there some utility that might clue me in to
the problem?

Thanks in advance.