Just completed first DVD with Tmpgenc, 19 episodes of vcd quality simpsons, with the chapters put in.

Used the make DVD video option of nero to burn on to DVD-R, yet after watching it for a whilek the annimation and audio become out of sync, obviously a bit at first, and by the end, its kinda unwatchable

I'm kinda new to this, so can someone explain=
*why this is happening
*what i can do to alter/ remove the problem?

Thanx