All applicable X servers for my video card S3 ViRGE GX2 (Diamond Stealth 3D 4000) cause after some time a total freeze of my computer, i.e. absolutely no response to keyboard or mouse events. A manual reset is the only solution. I tried the following XServers: XF86_SVGA, XF86_S3V and XFree86 with the s3virge driver. The bug can be reproduced by using the Gnome Control Center and selecting the Halo screensaver. This locks up my computer instantly. The current workaround that I use is to use the XFree86 server with Option "NoAccel" but this is noticably slower.
Is this a dupe of bug #23659? I can't try reproducing it with Halo, because I get an error when I try to activate it. (Unrecognized option -ncolors.) See if the bug happens with the Laser screen saver (i.e. select it in Control Center, then run xscreensaver-command -activate). If your X server hangs, telnet or ssh to your machine, run top, and see if X is running at 99% CPU. If so, then you're having the same problem we're having over at bug #23659...
Laser does not give any problems in my configuration. Furthermore, the problem is not just that the X server consumes too much processor time. I wrote a small script to echo a bell (^g) character to one of my virtual consoles. The beepings stops immediately when I activate halo, so it seems very likely that my entire system has crashed.
This bug is fixed in XFree86 4.0.2 that I downloaded from the rawhide distribution. The rpm package on rawhide initially failed to install on my system (a standard Redhat 7.0 installation). At first I did not notice that I was still running 4.0.1 so I assumed that the bug was not fixed. Only when I queried rpm a few days ago I discovered that the install had failed. After reinstalling (I had to remove the xkb directory manually) my system has been running fine.