Hi. I'm a software developer who is an experienced linux user, but not at an expert level. I have a vague understanding of some of the concepts behind X, but I am very poor on the details.
My problem began about an hour ago and, putting it simply, my X server appears to reset after about 10 seconds or so, just long enough for most of my desktop (Gnome 2.14.0, Fedora Core 5(*)) to have loaded and displayed. During this time, I get an error dialog relating to xkbcomp, but this has persisted for some time now, with no ill side-effects, and I have yet to find a solution to that.
After that short time, the screen flickers, very quickly, a single time, then flickers slightly slower and shows the gdm again. This occurs when logging in as a normal user. When logging in as root, I have no problems.
There is a lot of information in /var/log/Xorg.0.log, and the following looks the most relevant, to me. If anyone can suggest anything else specific to look for in this file, it would be greatly appreciated. I don't want to post the entire contents of this file (798 lines) here!
431 (WW) NV(0): config file hsync range 30-86kHz not within DDC hsync ranges.
432 (WW) NV(0): config file vrefresh range 50-130Hz not within DDC vrefresh ranges.
793 AUDIT: Fri Mar 31 19:38:22 2006: 6504 Xorg: client 2 rejected from local host
794 AUDIT: Fri Mar 31 19:38:22 2006: 6504 Xorg: client 4 rejected from local host
795 AUDIT: Fri Mar 31 19:38:22 2006: 6504 Xorg: client 3 rejected from local host
796 AUDIT: Fri Mar 31 19:38:22 2006: 6504 Xorg: client 3 rejected from local host
797 ProcXCloseDevice to close or not ?
798 AUDIT: Fri Mar 31 19:39:08 2006: 6504 Xorg: client 15 rejected from local host
Those are line numbers, and note that I don't see any errors (EE). I don't know anything about this file - or really about /var/log/ - but I'm assuming this is only generated on error and is for the user experiencing the problem. If this is not the case, dooe anyone know which log file(s) I should be looking at?
I heard about a similar problem involving the .Xauthority file so I regenerated that file for the appropriate user, but that had no obvious effect.
I recently changed gdm, and in the vain hope that the problem may have been a symptom of the change, I reverted back, again to no effect.
Many apologies for the length of this message; I wanted to provide as much relevant detail up-front as I could, to avoid wasting people's time. If you are able to offer any suggestions or advice, please accept my thanks in advance.
- Bobby
(*) I recently upgraded from FC4, manually. This was a tedious process necessitated by a yum error - I'm building up quite an error stack at the moment

Needless to say, this is not a 'vanilla' FC5 install, and if any specific details of installed rpms and/or libraries could prove useful, please let me know.