No, I save my prepared files to a folder where there are other files, but in a folder that has plenty of free space.

I meant that you should try saving your prepared files into a directory folder where there are no other files, of course.

I see. But why do you recommend doing that?

I guess you can do what you want. I thought you were looking for possible solutions.

Many suggest that you save your project as an ISO and burn that to disk using other software such as IMGBURN. It is more reliable and will help with your current problem.

What Vegas templates are you using to create your video and audio files?

Have you ever successfully burnt a Blu-ray with this system? if so when and what might have changed since then.

How old is the burner? The lasers do not last as long as the rest of the electronics.

Definitely try the suggested method of creating a BD ISO file with DVDA and then try burning it with alternative software such as Imgburn.

(It is a good idea to buy a rewriteable BD disc for experimentation purposes rather than waste good write-once discs.)

Thanks for all these interesting suggestions. In answer to your questions:

I use to render with Windows .avi (should I try other templates? Should I burn separately video and audio? - and how so?)

I did burn successfully in the past, but have not been able in the past several months, and cannot figure out what changed (aside from going progressively from Windows 7 to Windows 10)

I have 2 burners: one is incorporated with my Dell PC (bought less than 2 years ago); the other is an LG external, indeed much older (but burns DVDs way better than the internal!)

I will try create the BD Iso file and then use Imgburn (that I still have to download) - And yes, I will use a rewritable BD disc, after having wasted 5-6 of the normal ones!...

The first thing that you should do if you intend to make a Blu-ray disc is render to a Blu-ray compliant template in Vegas. AVI is not BD compliant. (If you are making a DVD, do likewise with a DVD compliant template.) Render the video and audio separately, using the AC3 Pro coder for the audio.

This practice will avoid DVDA re-rendering your files, give you better quality and will be quicker. It is unlikely to prevent you burning a BD, however.

In what way does your old external burner burn DVDs "way better" than the internal one?

I think you should consider getting a new BD burner. They are not very expensive.

How do I render the video and audio separately? (sorry for questions that to you may seem trivial; this is just my hobby in the little spare time I have, so I am no expert).

The LG, for instance, burned quickly a DVD that I had prepared in DVDA with the same footage (35 minutes), but saving it as a DVD, not a BD, after having changed the "properties" in DVDA. Something my internal burner just refused to do...

And: yes, I am going to get a new BD burner.

"How do I render the video and audio separately?"

Select File>Render As

For BD video you have two options for encoder

1) Sony AVC/MVC
With this encoder you have two options:

1a) AVCHD, which may include audio. In this case select "Customize Template, select the audio tab and un-tick "include audio".

1b) Blu-ray (video only)

2) Main Concept AVC/AAC
Blu-ray (video only)

Select a template that matches your frame rate and dimensions

Now render the audio using Dolby Digital AC-3 Pro encoder.
Select "Customize template" and set the Dialog normalization to -31 dB. This will leave the audio level unchanged during encoding.

Choose the same file name stem for audio and video. When you later load the video file into DVDA it will automatically load the audio as well.

"after having changed the "properties" in DVDA. Something my internal burner just refused to do..."

Perhaps your internal burner is not a BD burner, only DVD (and CD). Or perhaps a BD reader only, or it is faulty.

You're terrific! Thanks for the time and the detailed level of your info. I will follow your advice and play with these settings tomorrow!

It worked!!!! I followed to the letter your instructions: it took about 1 hour for the rendering of the video, 5 minutes for the audio, then the project imported in DVDA burned successfully (with my internal burner) in 50 minutes, and now I have a BD with my 35 minutes of high definition footage! I faithfully wrote down your instructions and will be sure not to lose them. Thank you so much!!