I am trying to monitor Excel behavior through events. To
do this I register with Application. If the end-user
manually closes Excel and my registration is still
active, the Excel process stays around in an un-dead
state until my process exits.

Suppose that I have Excel open with no open workbooks. If
the user closes Excel, I don't get any events. How do I
figure this out in time to remove my registration before
Excel tries to exit and hangs?