Demo crashes at Ubuntu 9.04 x86_64 (ATI card)

[Przemulala]

Hello!
I downloaded and installed demo of Penumbra: Black Plague at my fresh installed Ubuntu 9.04 x86_64. I've got ATI HD3200 graphics card with the newest x86_64 drivers (Catalyst 9.5). My computer has also AMD Athlon 64 X2 4850e processor (2.5GHz) and 4GB of RAM.
My problem is that after about 10-minutes play system crashes. Before this I've got no problems with the game, it works very well and nothing seems wrong. But then it catches freeze frame and I can see mouse coursor for a short while - anything I can do is just restart it (Alt=D and Ctrl+Alt+Backspace don't work)...
What's wrong? What I can do with this? I want to buy a full version but if it is going to be like this I won't.
Thanks for all help!

PS: Sorry for my English, it isn't my native language.

[pfloom]

I'm having a very similar problem.

After a while playing (during which the game works very well), the game returns to windowed mode, and while there's still some jerky mouse interaction possible, no keyboard commands work (not even ctrl+alt+backspace etc), and I pretty much can't to anything but reboot. I can get to a shell with ctrl+alt+f1, but "kill"ing the process has no effect, nor does trying to shut down x windows (telinit 3).

I'm using Ubuntu 9.04 x86_64 w/ AMD X2 4000 (I think) procesor, and an NVIDIA 9600 GT card.

I may or may not have found a solution, however:
Turning off compiz seems to stop it(running "metacity --replace" in the terminal). At least, it hasn't crashed yet after I've been playing without compiz.