You might do a search for Audio out of sync or some such things and you will be amazed by how many you find. Normally the situation occurs using .avi files, but it appears your mpg file exhibits the same thing.
I don't really have an answer, but possibly the codec used to encode your file does not work well with the Nero ones and gives you problems. You might check and see what settings you have for audio encoding and perhaps try changing those.
I did some LP to CD conversions using Nero and I found if I captured the audio using any format other than .aif or .wav (pcm) that the track divisions I set up and the track audio would not agree (not be in sync) after burning.
Something else you might try, would be to capture the audio and then reinsert it on an audio track. You can turn down the volume on the original audio so you only hear the added track. Maybe that would help, but it might make the file larger.