Ok, but I thought you weren't able to import m2v files onto the timeline in Vegas? Not in V11 you couldn't, so is this a new feature?
Secondly, are you sure the rerendering, even "with no compression" (is there a setting somewhere there for this feature?), won't affect quality? If not, should I use the same render settings for the whole as originally with the rendered pieces ?

Then, returning to the original question, supposing I'd try to render the three hours in predetermined parts, say five around a half hour each, with markers to mark the beginning and end of each piece, and V12 managed to do all of them, and then imported them into DVDA, would or would there not be visible breaks between the parts when viewed on the finished blu-ray?
One would think the separate files would run uninterrupted from one file to the next,right? If so, this might after all be the shorter route out.

Ouch! Didn't realise you were creating m2v. I stick with m2t so that I can smart render, then use the TMPGEnc method (do a search here) to make the finished file 'DVDA friendly'. What you're going to have to do then is play the un-complete file, take note of where it ends, then go from there. I'd stick with m2t, then complete it all with 11. You can run the m2v through tsmuxer or similar to make it Vegas friendly.

Under your general prefs tab, there is a tick box "enable no re-compress long GOP rendering". Make sure it's ticked. No recompress doesn't effect quality - it's literally not doing anything to the file. But.....you're just going to have to get by as good as you can with this aren't you?

DVDA will show a jump from one file to the next if you feed it several files.

One trick we use is to render to a Cineform AVI file. If there is a crash "most" of the time the part of the file file rendered would close and allow us to place it on the timeline. Simply take the section that rendered, place it on the top track, and start rendering again from that .
Hope this helps.

Thanks Zelkien, for the tips. I have had to covert many of the mov and mp4 sources I have in this multicam project into avi form, as the original source media would cause other mov files go blank (such as my Iphone4 files). This has led to a serious hard disc space problem, however: I am simply running out of space on the drive, as a few seconds of avi amounts to gigabytes in file size. But here's what I have done now:

I tried rendering the whole three hours with Pro 11 (the latest build 701), as I didn't use to have any problems with Pro 11, (at least not with build 683) but now it crashed too, and once again after rendering 11,1 GB. The first v12 crashes occurred @ 10,5 GB and 11,5 GB, so even though the crashes did not occur at the same spots on the timeline, there seems to be a pattern here.

I have the source files on the win7 system hd, with the output rendered onto another hd (prerendered files onto the system hd as well). The system hd has only some 85 GB free (out of, I think, 500 GB (writing this at work, so can't remember exactly), so could this now be a problem? (This didn't use to be a problem with V11, build 683, however. )

The computer is currently (so I hope) rendering it with V12 with CPU turned off and threads limited to 3, so maybe that will help. Though even if it does, it is no real solution, as Pro 11 (build 683) was able to render the three hours into two files (24 GB each) without a single problem.

BTW, does turning CPU off affect quality besides prolonging render times - the project is filled with CPU accelerated video effects, so of course I don't want these to be affected?

If nothing else works, I'll revert back to V11 build 683 and keep my fingers crossed.

Or if that doesn't work, maybe I should update QT drivers: could it be that build 701 requires the latest QT driver? As a matter of fact, I started using an older 6.xxx (can't remember exactly) driver when it turned out that the latest QT drivers (7.7 xxx) just weren't compatible with the various *mov file sources I have on the timeline.

Any thoughts?

You seem to be going around in circles Gabon, and making things ever more complicated. As I said in my first post, Vegas usually creates a file up to the point of the crash. You don't need to work with Cineform or avi for this to happen. If your source files are m2t (from HDV?) stick with m2t. I've been working with it for years with no problems.

Thanks, Arthur, for the tips. I wanted to stick to MPEG-2 as to me it looked better. So what I did was reinstall build 683 and bingo! all three hours rendered without a problem.

HDV/m2t is mpeg-2 Gabon. :-) Did you re-install 683 over the 701 release, or do a clean (read pain in the ar*e) install?