I used Pinnacle Studio 10 to edit two MPEG files (approx. 45 min each) and produced two MPEG files that tested well - sound was in synch with audio.
Then I used WinDVD Creator 3 (which I've been using for many months) to produce a DVD video (90 minutes) with a two scene menu.
When I play the DVD video (both before and after burning) it starts out with the sound in synch and then gets progressively out of synch. The sound lag approaches a second or so about half-way through the video.