1. Not a lot of RAM to use Classic
2. Are you an administrator? (should show that in Users Pref Pane)
3. Best way to start Classic is from the Classic Pane in System Prefs. If you're trying to double-click on Classic app in System folder, might not work every time.
4. try opening that Classic pane and check box to start Classic on login. that might work.
or....
5. Your permissions are messed up. Takes a Terminal Command to help that. chmod, or something, but I haven't needed to use it yet, someone around knows the right setup for that.