> Everything works correctly with a SxS manifest though so I'm at a loss here.

Does your test manifest include comInterfaceExternalProxyStub tags? Try removing these to see if failing in similar fashion without them.

These are need for multi-threading support usually employing COM's standard automation interface marshaller (or standard dispatch marshaller for events source interfaces) -- not sure if DirectCOM handles such scenarios.

cheers,
</wqw>