Burnt Dvd Skip

I get this thing where once I've burned a movie to dvd, sometimes the action scenes slow right down or just out of nowhere the movie will skip back to an old scene or ahead to a new one.

How do I prevent that? Is it that I'm running programs? I don't know of any running while I burn the movies. Or is it maybe the speed at what I am burning them at. Currently I am burning at x4 using Image burn and my dvds have a time of well they say DVD-R 4.7bg up to 16x 2hrs sp mode... hope that helps... thanks