Thanks for the swift reply. I've tried both the above and no joy. (I can't restricted drivers).
I've noticed a couple more things that may be of use with the diagnosis:
1. Upon bootup I receive the error message nivdia kernel not found..nvidia.ko cannot be found.
2. When I reinstall the nvidia driver, it reports that there is an existing nvidia driver and asks me to replace it. It then builds the kernel module, and gives a warning regarding "The nvidia-installer was unable to determine the correct X library installation path with the pkg-config utility. Please install the X.Org SDK/development package for your distribution."
Followed by "nvidia-installer was unable to determine the correct X library installation path and will install the NVIDIA X libraries to /usr/lib"
Not sure if this is related to my problem as the drivers still install fine.
Thanks for your help from a total noobie.