I had this problem in my old comp after every XP install; go to the Device Manager (windows key+pause/break, hardware tab, device manager) and reinstall your USB drivers.
Yes those are the ones I have and some other ones. This was my friends computer and I am no longer in possession of it.
I had this problem with my old computer. I think I will try to uninstall all of them and install the drivers I want for them. Hopefully he'll be able to do this over the phone.