Although I can still use my system and it is stable, I have been experiencing some very strange computer system problems. First I noticed that when I selected the Shutdown or Restart options, OS X would log me out instead. Then I noticed that Spotlight is categorizing my Applications as Documents. Also I am not able to create any new accounts. OS X did create home directories for the accounts I tried to create, but OS X doesn't recognize them as official accounts. I installed Tiger from my other Mac to this computer because my combo drive on this computer sometimes scratches disks. I don't know if that makes any difference but it ran fine for the first few weeks I was using it. Any advice on correcting the problem without reinstalling OS X?