Our incomming emails are not being routed to CRM.

I read the troubleshooting tips given in previous postings.
Everything checks out except this:
http://crmex/MSCRMConnector/ICrmEmailDispatch.SRF

When I access it through IE I don't get XML but an
internal server error.

The following works fine:
http://crmex/MSCRMConnector/ICrmEmailDispatchSDL.SRF

I'm going to try and re-register the dll as is indicated
but any tips are welcome.