I'm on Sonar 8.5 Studio 8.5.2.222 and using an Edirol UA-25EX external audio device (if that matters).    I can launch Pentagon 1 (need to open as administrator) and can use it for just a few minutes before the problem starts. 
 
After a few minutes of usage (trying out various patches and editing the controls), the CPU's on the track, audio device and master all peak out with a clicking sound.  As much as a try to disable that peak (clicking on peak red line), I can't get any other sound of the Pentagon 1.  All other soft synth's on Sonar 8.5 work fine but this one always seems to give me the same problem. 
 
I've tried to run/stop the audio engine - no luck.  I've tried to reset MIDI and audio - no luck
 
Has anyone else experienced this problem or have any suggestions?
 
 

Of course, I meant "volume" meters and not "CPU".

I have the problem too. As much as I love Pentagon, it's been a real hassle, and I'm about ready to give up on it.

I suspect it's a specific patch that's causing the problem. It will be hard to find though.

Read this http://forum.cakewalk.com/tm.aspx?m=2406560&high= and you'll be enlightened :)

+1 Popstarwannabe i ran into the same problem back in 8.5. i realized it was certain patches. after that i learned to turn volume down, throw a limiter on track and avoid those patches.