I was running into problems with my SanDisk MP3 player. I called up their tech-support line (NO wait... GREAT guy!) and he told there is a problem on SOME computers running XP sp2. When you try and run the beast off the cable the device isn't recognized. The device itself may work just fine...but the USB can't see it. The Microsoft article is HERE
Weird thing is I've used it on boxes before with SP2 and it worked fine. Might be becasue the battery in the device is getting a bit low.

