Burning avi to dvd with nero

Hi, I've been downloading .avi files and burning them to dvd. In the beginning, I had no problems...but lately i've been wasting dvd's. I have been using Nero Vision Express 3 and it will prepare to burn then a window with a whole lot of letters and numbers will pop up saying there was an error. I try it again and it says my dvd is not empty..im really tired of wasting my blank dvd's on this. I have nero ultra edition, can this be fixed or is there any other program on there that will help me? thank you.