Game freezes and locks everything =(

[switchcode]

i formatted my laptop recently and now run only ubuntu+compiz.
When I play tremulous, after a random interval it exits fullscreen mode, showing tremulous in a window, but i cannot control anything within tremulous or on my desktop. All that works is to ctrl+alt+backspace to restart gnome. Any ideas? Its not my gpu; Everything is turned right down to keep it smooth.

Im running Ubuntu Feisty with Compiz Fusion on a presario c300 1.7 centrino, 1g ram.

[kevlarman]

compiz doesn't play well with 3d applications, you shouldn't be running both at the same time.