This also happened on 2.6.32-un-def-alt5 (from 5.1) and that
xorg-drv-intel-2.4.3-alt0.M41.1 (when working in rxvt-unicode-9.02-alt1).

+++ This bug was initially created as a clone of Bug #23740 +++

The following problem can also be considered as a problem of the kernel: because even after restarting X, the screen stays blank. So, this means, the kernel doesn't provide a clean state for the new, independent X process. The kernel could take care of providing a clean graphics state for new Xs.

+++ This bug was initially created as a clone of Bug #23739 +++

Created an attachment (id=4453)
/var/log/Xorg.0.log.old when this happens

xorg-drv-intel-2.4.3-alt0.M41.1
# uname -a
Linux localhost.localdomain 2.6.30-std-def-alt15 #1 SMP Mon Dec 14 08:45:48 UTC 2009 i686 GNU/Linux
# lspci | fgrep -i vga
00:02.0 VGA compatible controller: Intel Corporation Mobile 945GM/GMS, 943/940GML Express Integrated Graphics Controller (rev 03)
# 

At random moments (often when opening a new page in chromium-browser-6.0.401.0-alt1.r47010), the screen is blanked (more precisely, filled with one color: black, or the blue color of the Chromium's window). One can successfully switch to a linux text console. But this state of the graphics screen stays "forever" until a reboot: restarting X doesn't help.

This happens rather seldom; and is not deterministically reproducible.