No, I haven't had that problem. I've had another problem (my DVD player was purchased Dec '99 I think). Some DVDs have ... well, a slight pause in them at one point in the movie. It doesn't skip any time, it just pauses for a moment.
A friend of mine had the same problem you had. He would have to hit stop and then play again, and the sound would synch up with the video. Other problems cropped up where it wouldn't even play some disks. He eventually just got another DVD player (actually a PS2 game player), and all the problems went away.
So, I'm thinking it could be your DVD player starting to crap out. Though I'm not certain. Could be the DVDs I suppose. Is your player an older model?