Comment 50 for bug 195051

I'm also having this same problem on my hardy heron installation. It's upto date at time of writing and uses an ATI Radeon 9800pro and the opensource ATI driver.

It will seemingly randomly lockup everything is unresponsive apart from the mouse cursor, i have accessed the computer in this state as SSH seems to still work and running the top command shows compiz.real using up all available cpu and using sudo kill -9 i'm able to regain use of that pc again (just loosing the window decorations).
If there is anything needed to further aid the resolution of this bug please ask and i can try to help (but with the freezes being quite random and my time limited i might not be able to check this report to regularly).

PS: I'm currently only assuming this issue is related to the driver, it could be compiz itself but reading this bug description and the related launchpad.net bug it seems more likely my problem is the same as described here.