Suddenly windows device manager shows you problem with graphic’s card driver with error code 43?
Please check your nvidia driver version, after some windows update on win7 the newest drivers are not working (inspite of the fact that they are detected as proper drivers). In my case I have win7 64 bit with geforce 6600 (but I know this issue concerns also newer cards). The solution was to manualy download older nvidia (in my case it was 195.62 version).
For older cards newests drivers are not so important, because new features that these drivers introduces aren’t supported by such cards.
The interesting fact is that on the same maching I have working nvidia-drivers-260.19.21 under gentoo.