I use windows 2003 server (japanese version) and I've tried many many codecs, programs, everything, and I can solve the problem
(I've also uninstalled/installed 10000000 times the video driver, etc)

the problem is that when I open a video, it's played, BUT there isn't any postprocessing, not even the "native" one, even if I configure it .....

I really don't understand how to solve this ... it works perfectly under windows xp, without any configuration :/

here's a screenshot of how is played the videos:

http://www.manganimation.net/temp/screenshot_sarasse_02.png

please help me

What directshow filter are you using to try to decode your video? Have you tried ffdshow or XviD? I can't think of any reason why post-processing won't work.