Comment 198 for bug 127101

There is also another solution to this, so far I find it a bit better.

What you do is:

blacklist video

(add 'video' to /etc/modprobe.d/blacklist)

add nmi_watchdog=0 to /boot/grub/menu.lst in the defopts for kernel, then sudo update-grub.

With ForceEnablePipeA I could not set my brightness correctly (ThinkPad X40). However, with the latter fix mentioned now, that works well, and I no longer suffer from the unreponsive black screen issue.

The glxgears performance is a bit lower than with i810 on 8.04.1, but I guess that's going to improve and besides, glxgears is not a good benchmark :-)

The fix is from:

http://ni.imasters.pl/content/ubuntu-710-oraz-804-i-problem-z-zamrażaniem-ekranu