On a random number of switches between users there would be appear a blank screen and a switch to one of the terminals and restarting X would do. However, continuing switching between users ends in a terminal system freeze with blank screen and a cursor blinking high in the left corner and the only cure there is is a HW reset. There is nothing in the logs on the subject to look for a cause. Similar behaviour happened when I was using the fglrx driver (regardless of version). I spotted a similar problem in Ubuntu's launchpad: https://bugs.launchpad.net/ubuntu/+source/linux-restricted-modules-2.6.20/+bug/107115 In my case I now use radeonhd driver, v1.1.0, git updated on 28.12.2007 and the problem persists. The fglrx module is not loaded in the system and the xorg files and configurations are attached to a Bug #13853.
This looks very much like a race that is not necessarily driver related. A blinking cursor on a blank screen indicates a console with no assigned VT is active (such as console 7 or 8) and the text mode has been restored by the driver. I assume the system is still responsive, ie you can log in from remote. What happens if you kill one (or both Xservers) from remote? Can you switch to a text console with Alt-F<n> or chvt <n>?
I hate this murphy thing. Now that I want to crash it, it doesn't. Will keep it open a tad more if eventually it comes to a freeze.
Bugzilla Upgrade Mass Bug Change NEEDSINFO state was removed in Bugzilla 3.x, reopening any bugs previously listed as NEEDSINFO. - benjsc fd.o Wrangler
Well it seems that it really isn't a driver issue anymore since it stopped behaving that way all of the sudden. I guess some gnome update has done the trick. Anyway, it only happens when a user logs out once that driver has changed (all while user was actively logged).
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