Wierd screen corruption with ATI Mobility 9000 M9

[Philip Balister]

I have a Dell 600m that uses a Radeon Mobility 9000 M9. Installing
Yarrow went fine. By and large everything works fine, however if
I leave it powered up for a "long time" (for example overnight, although
I think it takes less time for this to happen) the screen gets flaky.
Random dots/lines.

Here is a screen shot I took:

http://www.balister.org/~balister/bad_screen.png

Interestingly enough, it was just in the mode and I went to turn it off,
but decided to try restarting X to see if it cleared up, but it cleared
up before I could restart X.

Thoughts? Bugzilla it?

Philip