need some help with audio plz

[freebee22]

hi, this is the first time that I have encountered this....the audio goes out of sync after 3 to 4mins..the first 2 mins everything is ok but after that it just get out of sync....don't why...my method

1. rip the vob file
2. use dvd2avi demux audio
3. use tmpgenc to transcode the movie to make it fit a dvd
4. use spruceup to author..

I've tried this method several times and it works for me.. but this is the first time I have encountered this

anybody can help plz
thanks

[freebee22]

anybody out there plz..