If anyone is getting a window saying 'List index out of bounds' for every message that should be appearing, just use 'Ctrl-Alt-Delte' and close Subliminal Blaster that way. Don't worry that there's something more serious wrong with your computer - it's completely random. It's happened to me a couple of times and if you don't act fast those windows can flood your screen.
I found that if you don't fully exit the program after seeing this error it will keep doing it on session start, even after you manage to hit the stop link in between messages. A complete exit and restart fixes the problem so what BobbyS has suggested will not only stop the flood of messages but also fix the problem. At least until it happens again :)