Try trashing your Pro Tools preferences. From the Finder go to "your boot drive name" > Users > "your username" > Library > Preferences and trash DAE Prefs, DigiSetup.OSX and Pro Tools prefs. Then restart your machine.
If that doesn't work...
Try backing up, formatting your boot drive, and reinstalling Mac OS X from the DVD that came with your MacBook. It's important not to run any Software Updates unless DigiDesign approves them for Pro Tools. This is true for Mac OS X and Windows, it's just how DigiDesign rolls.