Beepster
Why? Why is it something in Sonar? Why is it ALWAYS something in Sonar?

Well, he DID change the thread title so it didn't have 46 exclamation marks!!!!!!!!!!!!!
 
But to give you a serious answer, most - maybe even the majority - of users don't realize that what they see in SONAR is the tip of an iceberg. They don't see what Windows are doing, how the computer is communicating to the interface, how the plug-ins are communicating with SONAR, the buffering in the USB port, the high-end graphics card driver that suspends audio streaming every now and then because it has its own agenda, the sample library trying to decide how much of a note attack to put into RAM when it's streaming from disk, etc. Because all they actually SEE is the SONAR GUI, they assume the problem is SONAR.
 
The worst-case examples of this kind of thinking are the posts along the lines of "I just installed a free 32-bit plug-in in my 64-bit system running SONAR, and now SONAR crashes. So I guess I need to re-install SONAR."

Beepster, you make some good points, and some bad ones.   So far I have not been able to find an "acceptable way" to get on with work, other than slow bounce with audio.   I guess it's one more in a long long string of work-arounds.    
 
I'm sorry if my post seeking answers, help, or fixes, seemed like pointing fingers.    Fwiw, I invested about 5 hours (again) in sonar troubleshooting; whether it is solely sonar, solely gplayer, or somewhere in between I still don't know. 

If the exact same MIDI sequence sent to two soft synths produces a problem in one and not the other via fast bounce with the exact same buffer settings etc, the chances are that the problem is with the synth. I'll be the first one to say that this logic is not guaranteed since on the flip side there are classes of plugin bugs that show up only in one host and yet they are actually bugs in the plugin!
VST (esp VST2) is a complex maze of operations that have state dependencies. i.e. the sequence of operations can often expose problems that are not anticipated. This can make it very hard to troubleshoot and find out where the real problem lies. For example it took many days to isolate the note off problem using a midi analyzer since I couldn't rely on plugins for my testing. 
 
So I do sympathize with the amount of troubleshooting you have to do in cases like this. If you can get some kind of recipe or send a small project that can repro it we'll definitely look into it.