OWA was working fine but now I'm getting an error with the following details: Name cannot begin with the '<' character, hexadecimal value 0x3C. Line 2, position 1. Nothing new in Add/Remove programs and I don't know that anything has changed.

I found the problem. Very weird. I was working on an ASP.NET pagethat performsAD password resets and copied the .aspx and web.config files to the wwwroot folder so I could test. Don't know why the URL https://servername/owa would try and use web.config but deleting it fixed the problem.