I've seen the sync problem at about the 15 minute mark in a 20 minute video on a Vegas 8.0a AVCHD project.

I also lose framerate at that point. I've tried the project at 5.1, stereo and even rendered the problem section in advance (which rendered fine) all with no luck. Most of the renders that I tried were 6 nested projects on the timeline with an AVCHD render using the Sony codec.

I think Sony still has a little work to do in this area.

Increasingly, I have to nest an edited .veg in a clean project in order to get a successful render, especially working in 32bit mode. Most of my AVCHD renders have been under 10 minutes so not seen those issues. With 5.1 sound, in one project, I got no audio and the other worked fine, so there is some inconsistency. As I don't have any AVC transport stream tools, I have resorted going back to MPG2. I can then mux the video and AC-3 together without issues.

I have noticed that if you use the Render As option, you use the Studio AC-3 codec. If you use the burn Blu-ray, it uses the Pro AC-3 codec.

In Pro 8a I did run across the audio not being encoded.
This was if I went in to the options and made changes without saving as a new template.
If i saved as a new template, then exited everthing, goto file-> render and select the new template then everything was OK.

*sigh*

Now even the blu-ray disk burning fails with error message:
Filename: STREAM/00001.m2ts

I have managed to prepare one .iso-file with the BD burn option but for some reason it now fails. I do not know whether it is related to the fact that I installed Vegas 7 to my machine to test surround problems... I uninstalled V7 but the error stays...

And yes, H:-drive has approx. 50 GB of free space.

Is that the source video you posted? ->Filename: STREAM/00001.m2ts
If that's the source is it mpeg2 or avc?

If that's the destination then that means the video & audio rendered and it's in the multi-plex stage before creating the iso image file.

The source was cineform intermediates and the project file is "Joulu 2006" ("XMas 2006", lagging a bit here, am I).

But thanks for the info, it will help me on debugging. I have installed a few ISO-extractors / creators lately and it may be so that one of those is interfering with Vegas. On the other hand I would like to see the possibility in Vegas to prepare the BD-material without the ISO-file. As it is in DVDA.

That is in the Multi-plexing stage. The program rendered an xxxx.avc and a xxxx.ac3 file and now has to multi-plex them together in a xxxxx.m2ts stream.
All this processing is performed under temp directories created below the directory you setup under preferences (the assigned working temporary directory for Pro).

Pro 8a had a problem when creating iso images (burn blu-ray disk). You need at least 3 times the size of the final project for disk space. Pro 8a did have an issue with disk space calculations (posted by someone after tech support help). Pro 8b probably fixed this.

You should be able to render a small test xxxx.m2ts file locally without going to a complete render creating an iso file, it's basically the same as the multi-plexed xxxxx.m2ts file your getting the error from. You should get the same error trying to render a separate xxxxx.m2ts file if usisng the same settings & templates.
I can re-create your error sometimes by using different fieldings or framesizes that I guess the program doesn't like (or they aren't compliant for the container format).
I would like to see the possibility in Vegas to prepare the BD-material without the ISO-file. As it is in DVDA.I've posted how to do this in Pro 8a, you can render a xxxxx.m2ts file to the local drive which is the same as the file in the ISO image. When I do have this problem in Vegas I render the project to a new unedited file, then load that and convert it.
Maybe search on creating a m2ts file, ah found the post back in December.
This is how I've been making avchd.m2ts compliant videos to use in other authoring apps.
http://www.sonycreativesoftware.com/forums/ShowMessage.asp?Forum=4&MessageID=567183
Maybe use a simple test file first, you will probably find the error using your project that's generating the error.
ISOBuster is a good program ($29.00)

The BD-problem is solved (kinda). For some reason I had Sony wave64 selected as audio format. When I switched it back to AC3, everything is OK.

I also checked the error and the file Vegas complains about. It is there but its lenght is 0. I will info the support also...

The reason why I asked about the possibility to prepare BD master w/o ISO-file is that because I'm having problems with the separately rendered AVCHD-material I'm checking whether this BD-thing will render better. And it uses the AC3 Pro codec whilst the Sony AVC-rendering uses AC3 Studio. Dunno, whether it makes any difference, though.