Don't use that Software, but there are some things you could explain/try....
First - is this the first time it's gone wrong? - ie normally when you do this it works fine, - so what have you changed recenly . . . hardware changes, maybe some new software, or updates, etc.
Secondly - are you burning a DVD and then watching that on yr PC - don't.
Burn a DVD and play it on a TV/DVD - unless yr PC is high spec it may struggle to keep lip-sync.
Finally . . . are you clear for the copyright?