For some reason nvidia have marked a windows update driver version as 'Important' so it's getting auto installed on people's machines.

I didn't check what updates were going to be installed when I powered off, so didn't see to block it, and now have a driver that's been downgraded several versions compared to the WHQL drivers on nvidia.com and I've have had to mess about downloading another 250mb, reinstalling and I think I'll have to reconfigure screen settings, cleartype, everything as it curently looks like crap :-/