I've got the same problem.
After installing the drivers for MP3Car XM USB adapter, things seem to be much worse, although it did happen intermittently before that. My Wireless keyboard and touch screen just quit working whenever they feel like it. Sometimes, before they quit working, I hear the XP chime for a USB device being disconnected several times in a row and sometimes I here nothing at all. They just quit working.
Sure would like some input on this one too.