I have a PC built for a friend running Windows Vista Home Premium. All drives except the C: drive are invisible in Vista's "Computer" window. The drives are recognized by the BIOS and Vista, and flash drives and the DVD drive are even given Safely Remove options. But, only C: shows up in "My Computer." Flash drives that are formatted and have a drive letter do the same thing, recognized & have a drive letter but not showing up. Any suggestions? Thanks.