I have two Win & home premium new HP computers. I have two different USB flash drives. Neither flash drive shows up on either of the Win 7 computers, yet they both work fine on XP. I checked disk management in case I needed to change the drive letter, but they dont show up. The flash drives are both formatted FAT - could that be the problem? Also, both Win 7 computers have no problem with my usb external hard drive formatted NFTS.