I typed like seven different things to that last post... and then deleted them all. Safer to stick with the cpu problem, since eternal damnation doesn't happen because of a blue screen of death
In any case, I hate to be the one to ask the obvious questions here.. But have you....
Removed all previous video drivers before installing the new ones? NV's got a bad habit of making their drivers incompatible with each other for some god-forsaken reason. (no pun intended)
BF tends to let you know with no uncertainty if it's been corrupted. It usually won't let you get past the splash screen. If it's still playing screwy after a reinstall, ( A full reinstall, registry wipe and all) then I don't know what to tell you.
How old is the hard drive/RAM ect? Anything else going wrong? Memory exceptions and long load up times for XP could be memory stick went bad, or hard drive's having trouble. You're an IT, you know the drill. Work your way backwards until you have a pile of computer parts laying at your feet and installation disks scattered all over the room. Aren't computers fun?
Hope it gets itself worked out.