[Suicide Junkie]

The menu that has the "play game" / "video settings" and such?
Yikes, that's not good.

Main tip:
- Never edit the stock files.
Instead, copy the campaign folder, and edit your "copy of campaign X".

I would suggest reinstalling SF as the most straightforward thing to do next. It sounds like something must have gotten corrupted in the exe... You didn't have a catastrophic failure lately? Power outage while loading or something?
Mught want to do a virus scan too just in case.