OK, I've fixed it. I was using a form to host MSComm but I never unloaded this form. Adding a Unload MyForm did the trick.

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>I created a SingleUse EXE COM server with VB. The problem I'm having is that it won't shut down after I kill the reference to it from the calling program. If I hit CTRL-ALT-DEL to see the task manager, I see my server still running, even if I exited the calling program.
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>I suspected an object reference somewhere in the code that isn't cleared, but I can't find one.