Having trouble matching audio to video?

I downloaded a tv show and burned it to a dvd. I am using nero 7 to make my dvd. When I play the dvd in my dvd player the sound doesn't mach the video I.E. the actors move there mouth and after a second you hear them speak. any way of fixing this? any free programs that will fix this? It starts out fine but by the middle of the show it doesn't match up.