Blank screen after 5/10 minutes of being logged in, frozen

[tr33m4n]

I am using Ubuntu Lucid 64bit, with all the latest updates.

The screen will go blank and the computer unresponsive after a period between 5 and 20 minutes... sometimes I am able to change to another tty and (blindly) restart the computer, other times I have to do a hard restart.

Attached is the Xorg.0.log, the contents of lspci -vvnn and dmesg

[tr33m4n (tr33m4n)]

Oh, just realised this is probably filed under the wrong project... I searched for xorg, this was the main result, but the project reference appears to be xserver-xorg-driver-vesa. I am using the open source radeon driver... am I in the right place? quite confused