Power mac G4 Dual 867 OS X 10.5.8. Computer was recently upgraded so I could I could sync it with my new iPhone 4. Everything worked great. I share this computer with another user, I come home from work, log in to my account, and I notice both the Safari 5.0 and Apple Mail icons on the dock show a question mark. Long story short, the other user had deleted the apps. I was able to rebuild the two apps, everything working fine. Next day, I find out that Quicktime (paid version) was also deleted, and the other user was in the process of reinstalling. Since then, the computer will not sleep. Also when using the Apple Optical USB Mouse, especially when scrolling using the track ball, the cursor disappears or leaves a trail. Sometimes there is just a little colored square where the cursor should be. I have used Applejack in AUTO mode, didn't change anything. Any help would be appreciated.