[newbie] X crashes entire system

[Chronos]

Whenever I log out of a user session under X (KDE, gnome, etc) my entire system
freezes up, does anyone else have this problem and what would be the solution.

I didn't have this problem under RedHat 6.1, SuSE 6.3, or any other
distribution.

My graphics card is a Diamond Stealth 3D 3000 using the XF86_S3V server.

thanks in advance