I have a Iomega Prestige USB external hard drive that I have used for 3 years hooked to a Linksys router as a network drive. I had some trouble with Laptop running Updated Windows 7. I hooked the drive to the Laptop and did a backup. After that if I plug it into either one of my Windows 7 computers I get the message "Drive must be formatted to be used". If I plug it into my XP machine it works great. What happened?