[SpecMode]

My PowerBook has locked solid twice in the last few hours, and froze once with the cursor still movable (not that it helped, since nothing else was responding). My current system setup:

PowerBook G4 15" 1.67GHz w/DL SuperDrive (October '05 rev.)
1.5GB DDR2 (512 Apple + 1GB Corsair)
100GB HDD with 29.9GB free
OS X 10.4.4
Path Finder 4 running in lieu of Finder
USB Overdrive running as driver for Razer Diamondback USB mouse
Quicksilver runs on startup
No haxies

If anyone knows of any obvious conflicts from the above list right off the bat, please let me know. To continue, here's what I was doing each time I encountered a problem:

#1: Was watching a DivX video in QuickTime Player; system locked solid (cursor did not respond, could not force quit anything, Ctrl+Cmd+Power would not restart). Restarted, verified disk, repaired permissions (no problems found), checked logs (no crash/error log entries found).

#2: Was playing Kill Monty, game locked but background music continued playing and the regular OS X cursor reappeared and was movable (system otherwise did not respond). Could not force quit app, but Ctrl+Cmd+Power restarted the system. Again, no log entries regarding the lockup were found.

#3: Watching a DVD using DVD Player.app, locked solid same as #1 above, except for a ~0.5 second endless sound loop. Once again, no log entries or problems with file permissions.

This being the third lockup in almost as many hours, I'm gonna start digging down to troubleshoot the issue, and I was wondering if anyone has experienced similar issues. Thankfully, I did purchase Applecare for this particular 'Book, so I'm (hopefully) covered if it's a hardware issue; however, I'm going to be spending the majority of the next month at sea and I'd obviously prefer to have a working laptop.

It should be noted that I did have to reinstall OS X recently (about three weeks ago) due to some kind of OS corruption (resulting from a similar lockup) that Disk Utility and Applejack could not repair; I'm wondering if the 10.4.4 update is the culprit, since I had just installed that prior to that debacle.

Any ideas?

[torifile]

Pull out that extra RAM and see if it goes away. Sounds like hardware to me.