Again, this may not be the solution for you but it was for me under Vista x64 OS, same card and same drivers
seemed to be ok under my XP OS.
I have an Acer 22" LCD widescreen monitor, the drivers I had were for 32 bit (XP), I thought they would work under Vista x64 as well but after a while, more apparent after playing games for a while, my Nvidia drivers were getting corrupt and/or having a problem with Vista because my pc would freeze, recover after a while or a cold boot would have to do to get it going again and then I would get to the point you are now.
After many attempts of going into safe mode, uninstalling Nvidia drivers, restarting windows under generic vga drivers and installing a fresh copy of it, sometimes, it would work, some other times, I wouldn't.
After many googles searches I came to find out that I was having a conflict between my Monitor, Vista and the Nvidia Drivers... not an easy solution was provided and Acer doesn't make 64bit drivers for my monitor.
Later on I found out that Acer makes another LCD screen, similar to mine that does have 64bit drivers. I took a shot, installed those drivers and I have not seen the problem again. This happened a few weeks ago (got to knock on that wood again though!
What I am trying to say after that long rant is... try to see if you can get Vista 64 drivers for your LCD. If you do, make sure your Monitor's name appears in the Device Manager under Monitors and not just a std PnP Generic driver