Like many others I've had trouble with audio sync in converting AVI to MPEG.

I seem to have fixed my problems this way:

Uninstalled every codec pack
Uninstalled every video converter app
Used Norton to clean the system up
Used a registry cleaner to make sure.
Reinstalled Ace Mega Codec pack
Reinstalled TMPGenc
Reinstalled DVD2SVCD

These three are all I now have installed.

Now all the AVI's that previously failed have so far worked perfectly.

Hope this helps others.