Anyone having the Problem of Nero Vision not saving?

Well, I used Nero Vision 3 and 4 and when I try to make a DVD film, I do all the menu's and all the little bits and press the Go button, it starts transcoding all the files and took 3 hours to complete, once I press ok, I check the folder, and it shows that it only saved 2 gig when it should of saved 4gig, I tried again thinking it was a one off thing and I got it a bit higher it was 3 gig, when it should of been 4 gig. Some times it's less that 1 gig, This is only happening recently, so I tried just STRAIGHT burning it but the disc I burnt when I play them, the voice and picture are not syncronised. What is happening??