OK, this has just happened. I've been happily using the create DVD projects for ages. Today, I decided to try to save a template I had created, to "favorites" from one I've created modifying one of the standard ones. VS crashed, gave me notification that it was closing. I then went and deleted the new template files from Favorites, brought up VS again, crashed again. Tried to open some old DVD creation files that I knew worked - now VS tells me it cannot open the file. Tried old old recipe of rebooting the computer through a cold start. Problem still there. Arrrgh!! Help! Running pro 2023.
New addition to the post - thought I would bite the bullet and buy the upgrade to Ultimate (only $20). I GET EXACTLY THE SAME ERROR AND CLOSE DOWN WHEN TRYING TO CREATE A DVD. Where's the emoji for tearing one's hair out.....
another new addition. PROBLEM SOLVED - I had deleted the new template from the 23 folder instead of the 26 folder.

Go figure, since I'm running 23...