Here is Nero's response to my problem:
Please download the tool "PVAstrumento" from www.doom9.org
Start the program and insert your video source file.
Now click on the button "Make PS". This will cause in one ac3 and one mpg file.
Afterwards please start a new project in Nero Vision and insert
both of the files.
Now burn the project, e.g. to a harddrive folder.
Is it working properly now?
If you have any further questions, please don't hesitate to contact us again.