OWA password Change

Runing 2003 OWA server connecting to 2000 exchange server. OWA change password error https;//500 – internal server error.
All works fine when 2003 connects to 2003 exchange server.
I know of the additional virtual directory configuration when going from 03 to 2000 and followed per MS. Still getting the same error. Does someone know of a trick or some checkbox or something I have missed. I know this requirs SSL, after all these changes and deletions, possible reapplying certificates? I’m at a loss here and open to suggestions!