WM9 on WinXP

[Arian]

I have install VLC 0.8.0 on two identical (by hardware) XP systems. Both with SP1. On one PC, WM9 files (avi or wmv) are playback perfect with the new VLC, The other one plays only the sound! Both PCs have Media Player 10 install. On both, MP10 plays all content well. Why is this happening? How can I “force” VLC to plays those files on my second system?