I'm running FireFox 11.o on Windows XP. I clean my history and cookies. I defrag. My add-ons and plug-ins are up to date. I've gone into about;config and played with the dom.ipc.plugins and changed them true/false each one. Why won't the videos I want to watch play smoothly? I use VLC media player and Windows media player and enabled and disabled each one to see if a video will play better on one or the other. No change on the players. Can you recommend anything else I can do to see why videos won't play smoothly?

Thanks in Advance.