CAN'T EVEN REACH MENU SCREEN! "CANNOT READ PROPERTY 'EXPPARAMS' OF NULL

Could someone please look at this error report for me please and tell me what's wrong?

My project was working just fine yesterday, haven't added any new plugins, etc, and now all of a sudden it won't even load. Trying to translate the error reports are usually beyond me, so could someone please explain what I have to do to fix the problem? I tried loading the backup from last night, and it had the same problem.

UPDATE:

Hey everyone, problem solved. Turns out that the actors file had become corrupted (don't know how that happened). Just a copy and paste job to replace it. Only wish that the error messages were a bit more straight-forward.