I recently upgraded to Nero 7 (ultra, enhanced) from Nero 6 and now I have the unsync'd audio and video problem with both Vision (220.127.116.11) and Showtime (18.104.22.168) that didn't happen with Nero 6 Vision.
After totally uninstalling Nero 6 with clean registry tools, the only codec changes I made were Nero 7 install related.
With Vision I can check the unsync behavior before burning when running the "Test" remote control. When running Showtime I can see the video slowdown somewhat but the audio keeps on pace. Windows media player and VLC have no sync problems with playing the source video.
I usually retrieve TV shows from the internet and burn them to DVD with Nero Vision. When I run Gspot on one of these files, I see the Nero Decode 2 audio code having trouble, but feel it's really a video (Xvid 1.2 SMP decode) issue.