Let us try 1-2 things and see if we can get the project exported and also learn more about the problem.
Can you try a export to WMV format?
Let us know if it works.
Also you could try a export to mp4, and change the mpeg compressor, when exporting, go to file format, default quality and then try different compressors,
if the above does not work, then we will need to look more closely at the project and see if the issue is caused by any effects or transitions.