1. Try SAFE Boot & Repair Permissions

2. If you have another drive, try moving the jum build over to that one & opening it from there.

3. If that doesn't fix things, then delete your LW prefs folder whilst LW is closed, Deleting LW Preferences folder in OSX. But before you do that, make a note of all your preferences settings. Next time you open LW, it will ask you to reset your options. Disable all options under Advanced -> Performance.