Interestingly I recently purchased Sony Vegas Movie Studio Platinum 9b and had exactly the same issue.
1. I used my Sony XR-500E (PAL version) to record 5 minutes of video with 5.1 Dolby Digital audio.
2. I extracted the MTS files and used Sony Vegas to put in very little transitions.
3. I then tried to render the movie to a M2TS file (used Sony AVC) with 5.1 channel audio.
4. The program was crashing like anything – sometimes without showing any error and sometimes showing an application error.
I got frustrated and reported this back to Sony without any success till today. But I also downloaded Sony Vegas Pro 9c and tried to do the same thing. Interestingly Vegas Pro won’t crash, but it will create a movie which is completely out of sync with audio. When I reported this back to Sony, they told me to use DVD Architect to play the movie as Windows Media Player doesn’t have the correct codec. I couldn’t find an option in DVD Architect to use it as a player. Sony support has been an interesting experience for me.
I am now trying the TSMuxer solution.