Yes, Brian.
I agree.
The only solution for me was to completely remove EVERY program on my system that had "2015" in its program name (using the terrific Revo Uninstaller and running under "Quick Uninstall" after selecting each program in the listing.
That does a "bulk" uninstall so you do not have to do it manually one after the other). This too AGES. (Make sure each program relates to Visual Studio though...all mine did.)
I then went through each step outlined in Brian Stewart's answer on Jan 28th at 19:00. I chose to install EVERYTHING in the Visual Studio installation (may as well just in case of need!) At the end of the install I found I had 77 programs now installed with the number "2015" in the program name.
Note that after the completion of the Install from the downloaded "ISO" (run under "Admin" authority) there was one final re-run of the Install again from the ISO (using "Repair" this time) to finally fix a "NuGet" package failure.
After that all was 100% correct. (With no need to re-install the C++ libraries)
I then performed a shutdown and restart and tested Visual Studio, loading a project I had previously created. (If you do not have one, then just try creating a project).
You may get errors associated with settings files missing, such as:
Page '3185ed96-1cbd-4381-a439-636973542e50' not found.
You must then exit Visual Studio and perform these commands from a CMD prompt (elevated to Administrator) in order. After each Visual Objects IDE opens up, close it and run the next command.
1.devenv.exe /safemode
2.devenv.exe /resetskippkgs
3.devenv.exe /installvstemplates
4.devenv.exe /resetsettings
5.devenv.exe /resetuserdata
Then perform a final shutdown/start-up and everything should work fine.
So after all this, I finally performed an "image" backup of my whole system so that if needs be I can at least re-install my system with Visual Studio correctly installed.
Brickbats to Microsoft for making installation of Visual Studio so painful.
After years of paying good dollars for this great programming environment I was a little annoyed that now it is free to everyone, but I guess Microsoft is making us pay in some way with our patience. LOL :-)
It was a very long and tedious procedure, but everything now installed without error.
Thanks so much to Brian Stewart for pointing us all in the right direction.