Its the problem for ur OS.......u have SP2 right.
u have to update ur pc or download drivers for ur usb ports.. another thing maybe that ur front face which consists of two usb ports may not be connected to ur mother board.
prabesh, October 2009
Might be my pen drive is damage and disk is not recognize
Tom, June 2009
edit
I can answer this question...
WHEN I INSERT PEN DRIVE COMPUTER DOES NOT RECOGNIZE IT?