I am running os 10.3.7 on a PowerBook G4 and more often than not can not open various system apps such as iphoto, ichat, safari, system update... From time to time I do absolutey nothing different and all these apps work just fine. I read somewhere that bluetooth may be affecting things and have tried to remove it without success. All other apps work fine; ps, word, illus. I would like to try to fix this without totally reinstalling the system software. Any ideas?