Comment # 5 on bug 1104851 from Neil Rickert

I have a laptop with sandybridge graphics, purchased in 2009 (I think).  I have
freezes.

What I have found out, is that the freeze appear to be related to brightness
change.  In particular, if the desktop dims the display, then it often freezes
when it returns to full brightness.

Using KDE, I set it to never dim the display (but I do allow switching off the
display after a period of idle).  And I don't think I have had the desktop
freeze since then.

I still get occasional freezes, though they are rare enough to not be a serious
problem.  When they occur, it is during bootup, before the desktop environment
is fully up and running.