Got a USB thumb drive the other day for some file storage and it came formatted FAT32, so I wiped it with Disk Utility and now it won't show up on either a new finder window side bar or in Disk Utility. When I left it the usb slot for a few days it showed up again! Showed as FAT32 AGAIN and wiped it again and same result! It also got quite warm to the touch. Any suggestions?