Why wont my Seagate Free Agent Go Flex External Hard Drive work?

When I plug it into a regular USB port, it works fine. But when I plug it into USB 2.0 or 3.0 it wont work. It also wont work when I plug it into my PS3. I have installed the drivers for USB 3.0 (I hope correctly), but that shouldn't make a difference when I try to use it with my PS3. help please!