i was having (i think) the same problem. "usb mass storage device" was showing up in the device manager, but the drive did not show up in my computer/windows explorer. i finally realized what was happening when i went to control panel/administrative tools/computer management. under disk management, the drive did show up and was assigned drive letter e:\. i was, however, already using e:\ for a mapped network drive, and the network drive showed up, but the usb did not. i just right-clicked and did "change drive letter and path" and assigned the usb drive to j:\, which happened to be my next available letter. after switching the drive to j:\, the usb drive immediately showed up in my computer/windows explorer. hope this helps, i know it drove me berzerk for an hour or so....