AccessViolationException on program shutdown

Hello,

I'm encountering the following unhandled exception in nddsdotnet40.dll when my application shuts down:

System.AccessViolationException was unhandled
HResult=-2147467261
Message=Attempted to read or write protected memory. This is often an indication that other memory is corrupt.
Source=nddsdotnet40
StackTrace:
at DDS.WaitSet.!WaitSet()
at DDS.WaitSet.Dispose(Boolean )
at DDS.WaitSet.Finalize()
InnerException:

I've traced through all my Dispose() methods and it doesn't seem that anything is directly causing this exception.

I dispose of my domain participant by calling:

participant.delete_contained_entities();
DomainParticipantFactory.get_instance().delete_participant(ref participant);

The code executes with no problems, my window closes, and then I see the exception in my Visual Studio debugger.

I don't use WaitSets in my application, so I wonder if it is something internal that is not being disposed properly?

Thanks in advance for your help.