EDIT:  I have no idea why the Sound Center had disappeared from the computer.  There wasn't a trace of it - It disappeared when installing X3.  Just now, after writing this post, I ran the X3 installer again, selected to only install Sound Center - there we go, it's back.---grrrrr - why was it dumped when I installed X3--?
----original post----
I opened a pre-X3 project-in-progress, and at first it kept crashing X3.  I opened in safe mode (shift while opening the .cwp file) and after a few tries, tracked the problem down to Cakewalk Sound Center.
 
Thinking maybe I needed to insert a new instance and hook up the existing tracks to it - I discovered that I can't find the plugin.  Now I've looked all through my Sonar VST folder, I've looked in Program Files - everywhere on the computer- I don't have it anymore.
 
---What happened--?!  Any ideas?
 
Randy B.