MSN and Firefox problem.?

Okay so if I am running both Windows Live Messenger and Mozilla Firefox everything is all dandy until I decide to watch a video via Firefox. If I am in the process of watching a video and somebody either sends me a message, or signs onto MSN firefox will crash. This only happens with MSN and no other instant messaging program. I have no idea why and I've tried reinstalling both and updating. Nothing seems to be fixing it. Any ideas?