Xvid is installed, I was converting a dvd
Now, to address your problem, see if you forgot to put a check mark on the "Audio/Video synchronisation" box. If you forgot, put one there and test it. If you DID put a check mark there, try to un-check it and test it that way. Let me know if it worked or not. Another possible cause might be the file source. Check the file that you converted to see if the audio and video are synched.