It could be several issues. But lets start with the basics. What format are you using. Are you burning avi files as data, or are you converting them to DVD format? Burning as data, your limits are based on file size (SL = 4.3gb or DL = 8.2gb). For burning as video, your limits are based on time (basic guidelines: SL = 2 hours or DL = 4 hours).
Assuming you are converting, then my first thought would be Nero. It's a burning application, everything else it tries to do, is average at best. Get a better conversion tool. ConvertXtoDVD would be my first choice, aside from that, try DVD Flick or FAVC.
You could also simply have a bad/damaged file and that is causing the error.