I have 1 song file and granted it is a long one, 11+ minutes and has a lot of plugins and automation going on in it so it often took an minute to load up compared to a new project with less processing...     when it was working I had a separate copy of it as Songname-newtools and remixed it with new plugins (slate everything bundle stuff) and neither of those will open now?   I click to open that project and it will show the little circle "thinking" for a half hour and never open.  Shows nothing going on in task manager, I force sonar to close (end task) reboot, restart, same thing on both versions I saved and the sonar auto-save versions.  Any Ideas?   This is for a band and I need to finish this up for them!  Thanks in advance for any help.

Try safe mode by holding the SHIFT key while opening the project. If it still hangs, try safe mode disabling some of the plug-ins.

Scook, I was able to open the project in safe mode.   Then I got a notice that sonar was in "demo mode" as I have not signed up for a subscription.   This irritated me because I bought Sonar platinum with a perpetual license on the last weekend that you could still do so.  I own it.    Frustrated as hell I gave into the inevitable today and signed up for a new subscription, installed the command center and updated it all to the current version of sonar platinum...   Now, NONE OF my existing projects will open!???  They all just "Think"   My faderport sits there going up and down....  but nothing else is happening.   Any help here?