audio lag on dvd

Hi people. I am not a wizzard with computers but I am trying to convert some videos to dvd using nero 6. I can import and edit the videos ok but whenever I burn them to DVD there is an annoying audio time lag on the dvd i cant get rid of. (about 1 second)I have tried all the obvious: updated drivers, uninstalled/reinstalled nero, The computer is 3 years old but has been upgraded with 1.2 GB ram and has a hefty video card memory also installed. Is there any simple tricks to sort it.