It seems that every time a program calls for a restart (like after an installation), my powermac freezes at some point immediately before the restart. The screen goes black, but the PM is still on, fans still spinning, and it stays in that mode until I hold down the power button for a hard restart. The same thing occurs when I manually restart or shutdown, with the difference being that the screen is blue with the spinning black graphic. I have performed a fresh install (erasing the system partition), repaired permissions but the problem persists. My internal drive is partitioned, with the partition I boot from being the 2nd partition. My system: 2.5 G5, 23in new HD Cinema display, Tascam US 122, iShock II, external HD from OWC. Thanks for your help!