I just re-installed Windows and am now having this or a similar problem. Every time I try to watch a video with the DivX player, it buffers to 100%, loads the first frame of the video with grey bars scattered across the bottom half of the frame, then crashes and closes Firefox. I had no codecs installed so I went ahead and installed the codec pack I was using for over 6 months with icefilms working perfectly and the problem still persists. It's driving me nuts not being able to figure out what is causing it. Before reformatting, 1 day ago, everything was working fine on icefilms.
I'm having this problem on all sites, not just icefilms so it may be unrelated to the topic.
FIXED! OK, so I overlooked the fact that I used to use 1.4.0 Beta 2 and NOT the 1.4.2 Beta 2 version linked on the homepage of icefilms. I uninstalled the newer version and then installed the older version and everything is working fine now. You can download 1.4.0 b2 from http://labs.divx.com/node/248
just ignore the strike-through as the links are still clickable. Maybe that might help you?