conversion problem

[craigievar]

Have an avi file that plays fine. Gspot tells me video is mp43 and audio Lame mp3.
Have converted it to mpeg with, Tmpg, Panasonic Encoder, Xing Encoder and Ulead Movie Factory and everytime get the same problem Audio go's out of Sync.(Sound after video)
Audio is not just out of sync but out by 3-5 seconds . Why would this happen just bacause of converting it to mpeg. Have spent days on this and just cannot seem to get anywhere. Know how to add silence to audio with Goldstar and then convert to mp2 and multiplex but cannot understand why sync problem occured. Is there another way to fix file.

[ZippyP.]

Check for bad frames?