I go get the UBUNTU LIVE CD. (see google)
Now I re-test the machine while it has booted UBUNTU from the CD (no install!) and see what happens.
If it works, the OS is likely damaged. If it fails, the machine needs repairs.
Whenever I attempt to plug in any external device (external hard drive, iPod or digital camera) in to my laptop via any of the USB ports, as soon as the device lead is inserted the laptop shuts down. The laptop will not restart with the device and lead still connected but will restart once they are removed. Once restarted the laptop works as it should. This is a recent problem - prior to this the laptop has been working fine with USB devices.
I have also tried connecting just a USB lead with no device on the other end to the laptop and this also causes shut down.
I have connected the external hard drive, iPod and digital camera to another laptop and they mount, show and transfer files as expected.