did you make any changes or install something new?

when or where does it show up at?

Are you even using a USB mass storage device?

I googled the title words but i need to narrow down the search terms- got back wayyy too much stuff to look through
unless you want to look thru the results - after reading some you might be able to narrow it down better, or you might see the answer you need.
http://www.google.com/search?q=USB+M...&start=20&sa=N