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User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.10) Gecko/20050909 Fedora/1.0.6-1.2.fc3 Firefox/1.0.6

Description of problem:
X startup fails on FC4 after upgrading using yum.
The machine worked well with FC3 but a few days ago I uppgraded to FC4. The machine still worked well so I did a yum update. Yesterday I rebooted, after that X11 fails at startup with a garbled display.
Output from /sbin/lspci -vvn and the logfile /var/log/Xorg.0.log are attached
The problem is the same running under the kernels 2.6.11-1.1369_FC4 and 2.6.12-1.1447_FC4

Version-Release number of selected component (if applicable):
xorg-x11-6.8.2-37.FC4.48.1

How reproducible:
Always

Steps to Reproduce:
1. Booting the system 


Actual Results:  Garbled display

Expected Results:  Login window should be visible at the centre of my display

Additional info:

The system is practically useless as it stands (I can log into it using ssh) 
One of the problems being that yum/rpm lacks a revert to earlier version option.
rpm --oldpackage isn't safe for applications like X11 where config files might be converted during an upgrade.