I have a model ST3500630A mounted in an acomdata external drive enclosure that keeps going offline after about 5 to 10 minutes. It is connected to a USB hub with 2 other drives also in acomdata enclosures. It goes offline when connected directly to the computer USB by itself so that rules out interaction with the other drives and the USB hub. I have swapped enclosures to test whether that was the problem - it is not.
I tried the Microsoft KB 908673-v2 hotfix but it doesn't help. Seatools for windows shows the drive as OEI-USB2 UltraDisk. My other Seagate shows correctly as ST3400620A.
Why doesn't Seatools show the ST3500630A correctly? Only the generic tests work and the drive tests fine in both long and short generics.
I would wonder if this drive came from a usb drive or a third party device of some sort. You should check our warranty validator to see if it lists it as a component device. If it does then you should contact the retailer who sold you the drive and try to get a refund or replacement.