I've been experiencing some weird problems on my Mac Pro for the last few days. It's a Xeon quad 2.8, 6GB memory and running 10.5.6, never had any problems with it before. So the problems I'm having is that some system applications becomes unresponsive (freeze and fun beach ball spinning). In most cases I'm not able to force quit the frozen apps either. Also, in the dock it says "Application Not Responding" when I right click on them (like it should), but when I check the "Force Quit Applications" window there is no such text (there should be some red text after the application name if I'm not mistaken). These are the apps that has frozen the last few days: System preferences, Disk Utility, System Profiler, Software Update, the main menu has also frozen at times. When I try to shut down the Mac Pro it quits all the applications as usual, but then just stops and shows the wallpaper and nothing else (so I have to use the power button on Mac Pro itself to completely shut it down. When I want to put my Mac to sleep it takes way longer than usual as well. Today after I had been away for a while I came back to see the screen saver active, but in my Energy settings I've set it to shut down the displays before the screen saver would activate so I have no idea why the screen saver was on... I have locked my System Preferences (with the little lock in the lower left) but when I click on the lock it just says "Authorizing..." next to it and System Preferences freezes (no password window pops up). I'm lost. I can't for the life of me figure out what could be wrong. I've used Repaired Permissions without any luck. (There was some error messages, but now I can't even open up Disk Utility again without it freezing directly at start up.) All I can think about is that something I've installed would have messed something up, not sure. The last days I've installed: Grammarian Pro X (trial), iWork '09 (retail) and Handbreak. (and I've updated other software like Adium, but I doubt that's the problem) Any help would be greatly appreciated, I've never seen anything like this before. Tried to search around but I'm guessing I'm not using the right keywords because I haven't found any useful information.