Mega 2560 - Device cannot start

Hi,

I've connected my board to my PC and it shows up as 'SM Bus Controller' when i update the drivers using the arduino.inf it says windows could not find a driver. When i update using let me pick from a list and then pick 'Mega2560' I get the 'Device cannot start error' see attached image. I've tried a few different solutions found on the internet but no luck as well as different usb ports.

The arduino board is showing that the power/on LED is lit when connected to the PC so i don't know what the problem is.

Any help would be appreciated.

Windows 7 x64

Has the board ever worked?