Could do with a little more description on the problem, please.
Since I don't have much to go on, I'll head for the obvious.
(Assuming it's a USB device), tried plugging it into all of the sockets to rule out a dodgy one?
Tried rebooting?
Tried anything else in the USB ports?
What does it say about the device in the device manager? (Control panel -> system -> device manager -> type of device -> your device)
How old is your PC?
Are both PC and Laptop running the same OS? (I'm stabbing in the dark a bit here)
And, as Dunc said, is it a USB 2.0 device and have you got USB 2.0 ports on your PC?
Sorry for the bad question. It is a 250gig external hard drive. I plugged it into both ports and it gave me this message:
This is weird because I always use this external on my pc and laptop. My iTunes on my pc is running off this hard drive so it was like all of the sudden it just stopped working. When I plugged it into the 2nd port, it said it was ready to use but it never showed up in my computer, so I turned it off then on again and it gave me the error message again. Same OS on pc and laptop, and the pc is around 2 years old.
And yes I clicked the message, that didnt help.
2nd Edit, It wont recognize my external hard drive, or my usb hub but it will recognize my printer. I would uninstall the hub but I dont know what it is under. BAH!