A solution has been found. Clinton Wittstruck, the support engineer assigned to my SR, was very helpful, and discovered the problem. He had me run a tool called ProcessMonitor, which logs all process activity. I ran it across the time I started an application with the MGCPCBEngines dll in use and causing a crash, and attached the output log to the SR. He checked it over and took note that I have been compiling for 32 bit processors, but have installed the 64 bit version of VX.2.1.
So I tried to switch the project to compile for 64 bit systems, and the SharpDevelop IDE gave an error message saying it could not compile for 64 bit systems. Maybe I am doing something wrong in the project settings. Not sure. But I switched to the Visual Studio VB.net IDE, set it to compile for x64, and it had no problem. It also shows all the needed COM objects, which the SharpDevelop IDE does not. And the COM object list shows the version of each item, so you can be sure to get the latest one when there are more than one version registered with the same name.
So Mentor has come through. Microsoft has come through. I have been a loyal user of SharpDevelop for many years, but it looks like I'll have to switch over to VS.
I will update my VX.2.1 template, compile it for 64 bit, and post up when it's ready in its own thread.