On occasion my MBP 2.5GhZ Leopard 10.5.3 crashes, locks up completely. Now in windows this happens a lot more granted, but at least when you press Ctrl, Alt and Delete it reboots. In OS X both the Force Quit command and the restart shortcut (Ctrl Eject) keys quite often don't work either. I use my MBP primarily in clamshell mode and it is a pain to get it out everytime to hit the power button. Is there a key combo that works flawlessly like Ctrl, Alt, Delete in Windows does?