Speaking of exceptions, here are two great error messages passed along by Dave.
This one might be the most verbose I've ever seen:
ContextSwitchDeadlock was detected
Message: The CLR has been unable to transition from COM context 0x15a948 to COM context 0x15a7d8 for 60 seconds. The thread that owns the destination context/apartment is most likely either doing a non pumping wait or processing a very long running operation without pumping Windows messages. This situation generally has a negative performance impact and may even lead to the application becoming non responsive or memory usage accumulating continually over time. To avoid this problem, all single threaded apartment (STA) threads should use pumping wait primitives (such as CoWaitForMultipleHandles) and routinely pump messages during long running operations.
[ For those of you looking for a solution to this, check the link that Josh posts below ]
This one, from Outlook, is just funny:
Window is disabled: cannot close. Check your code.