Woke up this morning with a message saying hard disk error, asking me to please run the hard disk test in system dignostics, any help would be appreciated cheers.

What you need to do is go to "My Computer" right click the drive in question.
Then "Properties>Tools>Error Checking", hit "Check Now"

There are commercial tools for this but best try this first.

I would however back up any important data now as your hdd could just be on it's way out.