I have a 4gb flash drive that as soon as i got it and plugged it in to my XP I formatted it using quick formatt. then put whatever I wanted to on it. It is detected and installed and issued a drive letter in 7 off a 4 port usb extension hub and have never had any problem with it. Do you think it is because existing flash drives that weren't formatted first before adding programs are fat32 and this is causing the problem? I also think mine is a sandisk. I lent it out so I don't know for sure.