I don't know how it happened, but when I insert Pentagon, all I get is the frame of the GUI on a white background.
 
Attempting to close/delete/replace it results in an instant fatal crash.
 
Any ideas people? I'm running Sonar As Administrator (I always do) as this usually fixes Pentagon related problems.
 
Thanks!!
 
Edit: I think I'll try reinstalling. 

There's a "valley simulator" in Pentagon that's been known to crash it, but I'm not sure how to disable that if it's how it loads - haven't used Pentagon for a years now.  Aside from that, I guess it's purely permissions, so perhaps a reinstall will address both that and the default load state. 

Yeah, I re-installed it again and it seems to be working fine.
 
Funny thing though, after re-installing (without Sonar being open), I opened an existing project, inserted Pentagon and the same thing - instant crash.
 
I reloaded Sonar, opened a brand new, blank project, inserted Pentagon and it worked fine.
So I then went back to my original project, inserted Pentagon once more and this time it opened perfectly.
 
Go figure.
 
I'll mark this one as solved

Weird...  But hey, if it works in the end I suppose it's all good!