I've had OWA working fine after a migration to 2010 w/o any problems. Then all of the sudden it's stopped working.
I can get the Login Page up fine. I enter credentials for any user and I get an Internal Server Error (500 Error) upon clicking the Login button.
That's it. Nothing in the logs regarding permissions or anything. I do see this error in the Application logs though:
Process MSEXCHANGEADTOPOLOGY (PID=1316). The site monitor API was unable to verify the site name for this Exchange computer - Call=DsctxGetContext Error code=8007077f. Make sure that Exchange server is correctly registered on the DNS server.
Sorry I don't have more to go on. But I can't seem to find anything out there to look into regarding the OWA 500 Error.