OK, have to ask the obvious up front: Is it pushed in all the way?
Second, did you ever see it before you reinstalled, or was it "never there"?
It could be a bad mp3 player - I had one, though my system recognized it, it wouldn't do anything with the SD cards...
I RMA'd it and Sager sent me a new one (that works), even though they said they could not duplicate the problems I had (maybe it was my laptop?); anyway, like I said, the new one did the trick.
As for the drivers, you shouldn't need any, as it is a generic USB mass storage device, and the drivers are built-in to Windows.