no sound near the end of the film

[Smokey And The Bandit]

I am encoding a Xvid to DVD in TMPGEnc. The problem that i having is that once i have encoded the films to mpeg2 (dvd) there is no sound for the last 30 minutes! I never had this problem till i reinstalled my computer! Can any one help me?

Oh and can some one tell me where i can get the plugins for TMPGEnc!!

Thanks