Jeff,
Oddly, I just finally got my code to crash. Based on one of the examples I had seen in the past, I put a Namespace - End Namespace around my code. I built a "Hello World" button and it successfully ran. I noted that it did not put Namespace in any of the wizard generated code, so I took the reference out. Upon recompiling, as Arc launched, the Breakpoint went hollow, but when I pressed the button on the toolbar, it fired the code and went to the refilled in breakpoint. It immediately crashed on the second line of my code, but its the first sign of progress I have had in over a month of dinking around with this stuff.
Does your code have use Namespace, or is that not an issue in C#? Hope you can figure it out.
Dale