xvid codec problem

i have ace mega codecs 5.93 installed, just play mode [also tried 6.0 full&just play] anyway whenever i click on a movie that uses xvid in windows explorer i get an explorer eror and it says that xvid.ax is involved or caused the eror. i just did a fresh install of windows and this is the only codec i used. after this i also tried installing xvid v1.1 but the same. what can i do cause this is pretty annoying. by the way if it matters i have an amdx2 3800+, msi k8n sli platinum, 7800gt, audigy4 pro, leadtek 2000xp expert tv tuner, 1gb ram corsair xms