diagnosing USP conflicts

i have a user with a IBM T40/XP machine that recognizes all USB devices except one. other machines recognize this device readily. i unplugged all the USB devices and had only this one device plugged in but still XP didn't recognize it. what is a good diagnostic software that would help to show conflicts in this case. i assume it is likely a driver conflict. does XP have the tools to do this or 3rd party? thanks in advance.