.....after several months of chasing around this phantom, intermittent crash of the PCS-BusCM.dll module, we finally decided to ditch everything and return the source.
 
A completely fresh install of Windows 7 64 bit SP1 and a completely fresh install of Sonar X3e and absolutely nothing else. No other apps, internet, virus protection, additional drivers other than the current audio, no onboard audio and completely disabled in BIOS, and all the Sonar installations done as admin with no 32 bit plugs anywhere! Not even the beloved Perfect Space ( which you don't find out until later that it's actually 32 bit.
 
We were even thinking that there was possibly something corrupt about the original X3 download so we went though the entire download procedure again just to be sure it was a completely fresh install. And then did a 'vst reset and re-scan' just to be sure we didn't miss any steps. Even checked msconfig to make sure the ONLY thing starting up with windows was the audio driver, unchecked everything else.
 
Brought the Studio to a complete standstill for 2 days while meticulously thought each step through, you all know how this goes lol. So the brand new install runs like a Maserati, smooth, fast, and stable as a rock on the most demanding of projects with loads of effects and tracks....
 
....and then...BAM!!  
 
 
 
We literally could not believe our eyes!!! The same crash!!!!  Unbelievable!! On a completely new system.
It happens with the exact same frequency ( about twice every hour or so ). Only happens on the opening or saving of projects so far, or so it seems.
 
I read through every one of Noel's post about the registration of the Shared Utilities/internal path and checked the registry to make absolutely sure those paths got written correctly. All there, all correct.
 
That's about as thorough as I can figure an install to be and yet, there it is rearing its ugly head once more. It does not appear to be any one project specifically as it will happen opening one and then that one is fine but happen on another. We had never seen this error until we installed X2. It never happened on X1 or earlier, even with the heaviest of use and careless operation ( deliberately inserting busses durring playback, ect. ) 
 
And just to be clear, this is the exact same machine and components that X1 ran on. So far, this is the most pervasive problem we have ever had on any of our machines to date. A complete mystery so far....
 
 

...several mini dumps sent to the amazingly helpful guys at Cakewalk but they are as stumped as we are at the moment.

One of the significant changes between X1 and X2 were the MS runtime libraries needed to run the application. These may need updating on the machine. May want to suggest this to tech support.

I was under the impression that the MS runtime libraries installed with each app or plug needed to be those specific versions because that was the version used during coding. No??
 
I have several separate instances of the Microsoft Visual C++ 2005 redistributable alone in Add/Remove Programs and many other versions as well from several years. Each installed by either Sonar, Ca2a, Concrete Limiter, ect. 

In an ideal world this is the case. But they do get jacked up and when not right cause some fairly bizarre problems.

So do you suggest to update each separate version of the Microsoft Visual C++ 2005 Redistributable ( 8.0.61001, 8.0.56336, 8.0.59192, 8.0.61000 ) or is there simply an update for all the 2005 versions, 2008 versions, ect?? 

Since you are already working with tech support, I would rely on their guidance. They know which versions are used by each version of SONAR.

I think for the moment, they are about as stumped as we are, and this is about as typical as you can make a Sonar installation really. There is literally nothing to conflict with lol

Just ran across this post From Noel,
 

Noel Borthwick [Cakewalk]
Do NOT uninstall the CS runtimes or you will break some application or the other. If its on your system some application installed it because it needs it!
We install 2 flavors because we redistribute certain plugins that are not built by us. These plugins require the older runtimes.
Additionally there might be multiple versions depending on which service pack is being used by the various vendors. Executable files in Windows now have a manifest inside it that identifies the specific version of the runtime that it was compiled with. If the runtime is not found the application will fail to launch.
 
So do not remove any versions on your machine unless you really know what you are doing.

 
Hmm, this would indicate that the install needs that specific version even if its older.

I'm running the same Windows version and same Sonar version and have never seen this problem. Although admittedly I don't use the ProChannel much. Not that that helps you much, I just mean to say that it might be worth figuring out what is different about your machine. I guess you did run Windows Update until you had the latest everything?