Screen freeze leading to crash...help?

i recently reinitialized my start-up drive, reinstalled the software, and have run into a problem with PTLE i never had before. i'll be listening to playback, when i notice the screen has frozen even though the playback (audio) continues as normal. the mouse will move but no affect anything. (unplugging and replugging the mouse USB gives me one move before it freezes again.) i can however, using key commands, save the session, however i can't quit PTLE. Apple-Q or Apple-W leads to a soft crash -- the mouse will move, but the computer stays hung on PTLE. and i have to force-restart. i never had this problem before... PTLE never crashed on me, ever... anyone have any ideas. Dual 450 G4, 320-something in RAM OS: 9.04 running PTLE on its own. kind regards, tom.

Is the Energy Saver Control Panel active in your extensions set, and Sleep set to Never? It should be. If the ESCP is not active, it will default to sleep after a certain time, which will cause Pro Tools to crash. Likewise, when you do a new system install, the default setting is set to sleep. Also, you should install the Apple Multiprocessor Fix:

energy saver is off. so it ain't that. i will the multiprocessor fix... do i have to update my OS for that ('cause i kinda like 9.04... never had any problems with it)?? thanks for the timely response, too. tom.