Re: OMA redirect to exchange directory
Undo what you ever you did for 817379, turn off FBA and remove the redirect completely.
Then run IIS reset and test again to ensure that OWA works correctly.
817379 has some flaws in it, specifically that if FBA is enabled when you do the procedure you bring the problem with you. FBA needs to be disabled with integrated authentication enabled on the virtual directory before you start it.