I fixed this specific error, actually, by deleting the KSManager.temp inside the folder of the level I'm working on. It didn't seem to contain any valuable information...
However KS Manager still crashes every two or three screens I open, with the same error message. I can't seem to trigger it right now but it's very common. It says "Macromedia Fusion Stand Alone Application has stopped working. Windows is looking for a solution to this problem."
It's definitely tolerable, just a little frustrating.
EDIT: Here's a picture.