Thanks for the quick reply!
It was a clean install, I actually had a huge amount of problems with the system until I was told I had to do a clean install which I did, and yes I'm running the 64-bit version.
I've updated to the latest Catalyst drivers recently which didn't do anything. I've just updated them again, see what happens. I also just tried updating the Motherboard chipset, but it's telling me that I have a newer version already installed.