My problem is quite similar.
My situationis :
I played some muisc videos one by one (several minutes for one video) using mplayer. After 3-4 hours, the video card signal will disappear.
I use RedHat 7.3, KDE and the 1.0.4363 nvidia driver.
When I view the detail of post here, I found that people usually fact this problem when they logout and re-login to the X-win. But, for my situation, I login only once a day, and then play the videos for the whole day.
Therefore, the "restart X " solution is not suitable for me.
I also read the message in /var/log/XFree86.0.log. But I can't found any message about server crashing.
Dear all, do you have any suggestion to me, I am very annoying by this problem.