Bit Defender is a fairly aggressive AV program... When you did the ST update was the file popup generated by BD? It is usually good practice to disable antivirus software during installations to avoid this (provided the install is from a veritable source).

No there was no PopUp.  I never disable Bit Defender and I've done dozens and dozens of updates and installations of various plugins, DAWS etc. The reason I have BD on the studio computer is because it's used for financial transactions as well although not for general web surfing.
Anyway the issue appears to be solved as X3 has loaded and functioned perfectly after 3 cold boots with Bit Defender running and up to date.  One of those Ghost in the Machine deals I guess. In a way the problem was a blessing. Due to the frustration caused by the issue it inspired me to get out of the studio to clear my head and I ended up having one the best days of hiking and photography I've had in a very long time. So perhaps there was some Divine Intervention at work...........:lol:
Now I just have to work on the Melodyne issue which is no doubt something simple.  I had it working before but now it won't show in the Region FX.  It's installed because it does show in other DAWS.  I'll be working on trouble shooting that issue later today...........
 

The suggestion of temporarily suspending antivirus software is something worth considering - I myself have had issues in the past with some antivirus software running while downloading (corrupted files), and installing (weird errors).  They were not suggesting REMOVING your antivirus software - per your indications you like the one you are using.  The suggestion is to only suspend it while doing your installation of the music software, and then you can make the antivirus software fully active right after you complete the music application software installation.
 
Hope that helps - it is just something to try, if still having issues, that does not involve making any permanent changes to your antivirus software, so it is certainly super simple to do and just as simple to undo.
 
Bob Bone
 

Like I said I've done dozens of installs and upgrades and never had to disable Bit Defender. Including two previous upgrades to Sampletank and Sonar. Thanks for the suggestion but I don't see a need.
Anyway Sonar is working fine now but something has gone wonky with Melodyne in the process.  I had it working just fine before but now it won't show in Region FX.  I'm reading the help file now but I'm doing everything the same way as before. It shows up as a plugin and shows as being registered. Just doesn't show in Region FX when an audio clip or region of an audio clip is selected.......

The VST3 version is used for Region FX. Is the VST3 version showing up in the "Default all plug-ins" layout?

Thanks I can back to say that the VST 3 version was not installed.....installing as we speak.  Should work.....I'll let you know.

Yep that was it...........thanks again.

Oh and while I'm here pestering the heck out of everybody.  During the time I was getting the crash on open issue I disabled the popup box that allows you to choose which project you want to load when you first start X3.  Can't seem to find the option to turn it back on...............

Help > Quick Start...

The fastest way to install a different format of Melodyne is right-clicking on the Melodyne Singletrack entry in the Windows Control Panel > Programs, selecting change from the context menu then modify from the installer dialog.