External Hard Drive

Ive got a 500gb samsung 3.5 hard drive and have this put in a quickport combo docking station so useing this a temporary external hard drive.

All was well for the past 2 weeks as i was moving files from my pc to the temporary external hard drive it just stopped.The pc wont see the drive for a few seconds then vanish.
The hard drive powers up then shuts down.
If you dont connect it to the usb lead it will power up ok and spin but as soon as you connect it with the usb to the pc the spinning stops and the external Hard Drive shuts down
Ive tried 3 usb leads
Ive tried to use this in my laptop and same thing happens
Ive put other hard drives in the docking station and it works for them.
anyone got any ideas on this?
Is the Hard Drive itself broke?