GPU wont jump off idle clocks?

Just went on skyrim and was hit by a massive lag fest (<20FPS), was wondering what was the issue and noticed that my coreclocks arent getting off idle, currently the nvidia drivers make my gtx460 go from 50 or 100mhz core at pure idle and when i had audio going off the card or watching bbciplayer it can jump to 400, next stage is the actual load clocks of 700, overclocking hasnt budged it either.

Any ideas why it wouldnt be switching to the actual clock speed? I updated my drivers from the beta to the signed ones which might be the issue but im wondering why would it cause this?.

i had it with the latest after a driver crash, a reboot fixed it.

excellent! Should have done that really, just assumed since I was prompted to restart and did that it would work :D.
Thanks