platinum freezes at load, show project change, waiting for input

I feel that I've read about this problem here, but didn't find it using google (wrong search words, no doubt) ---
 
Sonar Platinum K version, windows 7; no changes to system or drivers
 
a saved project appears to load fine, but immediately shows as changed (has an asterisk beside the project name).    Does not completely refresh all windows and will not take any mouse or keyboard input.      
 
According to windows 7 Task Manager, Sonar is "waiting for input".   No other programs running, low but not zero CPU usage -- SONARPLT.exe using about 8 percent, higher than normal but low enough to easily start other programs.   No network.
 
If I end the task with task manager, and restart Sonar, I can load other projects including older versions of the same project. 
 
Any ideas how to find out what Sonar is waiting for and how to get to the point of providing input? 

There may be some, but I cannot get to them in any way.     I've tried mouse click everywhere blindly, Alt-Tab, Ctl-Tab, all keyboard keystrokes, Scroll Lock.     And I don't know what dialog would be present.  
 
But as typing this I had an idea --- after yet another render midi oddity, I disabled some of the audio outputs last session of work.       I imagine Sonar is trying to ask me if I want to re-enable them, only it is doing so in a hidden and impossible to access way. 

On Windows 10 (Windows Key + Tab) will present all open windows.
 
For Windows 7 try this  (Ctrl+Windows logo key +Tab)
 
Edit to add. If you have dual monitors move the main window to the other monitor. This should reveal any hidden windows.

If this happens again try hitting enter.