If you are unable to launch FCP 7, try deleting your user preference files for FCP 7.
This is a typical occurrence in public labs that are shared by many individuals – who also happen to be working on their projects on multiple computers. Not to worry – it’s easily fixable.
Follow these steps:
1- Quit Final Cut Pro 7
2- Double click the Hard Drive icon on the desktop
3- Navigate to your “Home” folder
4- Go to Library > Preferences
5- Locate – com.apple.finalcutpro.plist
6- Trash this file
7- Find the Final Cut Pro User Data in the Preferences folder
8- Find these three sub folder and throw them away
– Final Cut Pro 7.0 Prefs
– Final Cut Pro Obj Cache
– Final Cut Pro Prof Cache
9- Empty trash and restart the computer
10- Set your scratch disk using System Settings