ERROR: cuLaunchKernel() 999

[corex]

Nah, it has nothing to do with the OS.

I suggested downgrading just because I'm using those drivers.

One last thing.
A fellow coder had some issues with sm_21 lately(that's your card's architecture), so my last suggestion will be a wee weird: go to pluscat\kernels\4318 and rename ALL the sm_20 kernels to sm_21.
Actually, I've done this for ya, so just download this archive and extract the contents to the folder I mentioned above, overwriting current kernels.
It'll be a Frankenstein, but it'll should still work(if the 999 error is gone) with minimal speed loss.
Try that and let me know if that changes anything.

Thanks for the help I really appreciate it, I'l try it later when I got home...Thanks again mate...