I have the same problem.

Whilst running Limewire, the video in WMP, and MPC doesn't show. I have XP Codec Pack 1.3.0 installed, and I also tried KLM Codec pack as well. If I close Limewire, video shows, if it's open, it doesn't. I've also noticed the text on Limewire become a lot more fuzzy, but it's late at night. Fuzzy as in cleartype/java app kinda fuzzy. Not I'm drunk/high kinda fuzzy.

I also re-dled Limewire and reinstalled it, same thing going on.