Ussually thats a sign of conflicting codecs, which tends to come about when you instal codec packs (Nimo (sp?), DivX codec pack etc). Generally when that happens to me, I uninstal my video codecs and reinstal them. works like a charm then. Avoid all codec packs (except Matroska Codec Pack because it isn't exactly a codec pack), and use single codec installs.sohcan said:Perhaps I have just had a bit of bad luck, but I started coming across files that wouldn't play in either of the players you mentioned. Outside of that I spend basically all of my non-gaming time running linux/bsd and I found vlc ran beautifully for me on any os I run. The whole conundrum was solved for me with an all in one client that runs on any os similar to the way I managed to find a nice all in one messenging client. I don't mind tinkering sometimes but some things I prefer they just work, and I find vlc does. But then again I am not the world's biggest microsoft fan these days.
check that link out if you want some info and advice for video codecs.
I have no idea how codecs work in linux, as all this is for windows