Yesterday I tried downloding the X11R6-contrib package with urpmi. Unfortunately it got the files from a cooker source and since I wasn't paying attetion, I ended up downloading a new version of XFree86 (4.3-19mdk). On my next reboot, all my video stuff screwed up.

Loading a normal kernel works until X loads. At that point, the screen goes black and the computer reboots. I can only run in failsafe mode, where linuxconf lets me boot to initlevel 3.

I've uninstalled the -19mdk versions of XFree86-4.3, XFree86-server and X11R6-contrib and replaced them with the -5mdk versions. However, I can't get X to load in any way (by loading a normal kernel in initlevel 5 or by running startx from initlevel 3). I've tried generic drivers - I get errors. When I try with my old XF86Config-4 file (I fortunately had it backed up), the system reboots. /var/log/XFree86.o.log has only one error:
I have no idea what that means.

There might be other problems though. Initially linuxconf was giving me this error:
/dev/snd was a broken symlink. I don't remember why, but I deleted it. Now I don't get the error message, but those things aren't likely fixed either.

I would like to completely delete and reinstall all my X stuff. Is it enough to delete XFree86-4.3, XFree86-server and X11R6-contrib or are there other packages I need to get rid of? Or is there another problem other than X?

If it matters, I'm running an ATI Radeon AIW 8500DV.

If you haven't already done this, totally uninstall anything X related. I don't know what the package names are in rpm but you'll have to look around and see if the system will boot without error into console. Once that goes smoothly, reinstall (an appropriate version of) X and see if you get errors. If all else fails get youself a knoppix/morphix/whatever else live cd and boot off that. Then pillage the /etc/X11/XF86Config-4 file.

There must have been something wrong with the -19mdk release. Once the -20mdk release came out, I installed it and everything worked fine. I was able to get it all fixed up by booting with failsafe then going to init level 3.

Excellent.