linux freeze
 

Hello,
i have this weird problem, since i started using compiz fusion (which i know is not stable) sometimes when i scroll up with my mouse - in firefox, the system freezes, only my mouse keeps moving, but nothing is responding, not even Alt+Ctrl+F2 (or Backspace). anyhow - i will try to fix this my self, my only question is, after i reboot, is there a log file somewhere that i can see what was the last thing that happend before the comp froze? thanks.

look into /var/log

yep, in the /var/log dir you'll have all the log files. /var/log messages will probably be of the most interest to you.
Just more the messages file
:> more /var/log/messages