My command - tab shortcut stops working after a random period of time and I have to restart my MacBook to get it working again. Any idea what could be causing this keyboard shortcut to fail? I tried killing and re-running the Dock but that does not fix it. A refuse to reboot my Mac everytime it happens (this is not Windows...) Any ideas on what might be causing the problem?
Try repairing disk permissions ...
Launch Disk Utility. (Applications/Utilities) Select MacintoshHD in the panel on the left, select FirstAid, then click: Repair Disk Permissions. Quit DU when it's finished and reboot.
Actually, I figured this out. Since my MacBook is my work PC I had added to SMB drive mappings to my login. When I was not connected to the network and these drives could not mount was when I lost the ability to task switch. I removed the automounts from my Mac login and the problem went away.
I also have this problem with a MacBook Pro (Early'08). The four finger gesture still works to switch apps. I do not have a screensaver process running. Any ideas?