If you want some great support, head over to the EVGA forums, we've got a lot of experience working with those nForce boards and driver issues, even if your board isn't an EVGA brand, we can probably hook you up.
My best guess is that you need a proper driver pack - the 15.xx and later nVidia driver packs are problematic.
Check out this troubleshooting FAQ I did on the EVGA forums for their 680i series. Most, if not all of the advice there is applicable to all nForce-based motherboards. Specifically, check out the section where I discuss getting the right drivers.
Troubleshooting FAQ: 680 series boards
Don't be afraid to sign up an account and post your issue over there. The forum community is absolutely wonderful and quick to reply.
Should save you some money and the hassle of re-installing an O.S.