screen saver does not start

It is Vista Ultimate, before I had business until about 3 wks ago when I
downloaded and installed an upgrade (optional) for my e-GeForce 7600 GS
graphics card. The screen went black and never recovered. I had to reinstall
the new OS.

My question is about why my screen saver won't start. I think I went through
all the motions. I recall that I had the same problem with business but no
entirely clear since at that time I did not need it and hardly paid
attention.

Thanks.