We recently ran a .NET update on our Exchange 2003 server and after that we have been unable to use OWA or ActiveSync devices.
We have gone in and recreated the virtual directories and we believe we have checked everything in IIS but its possible we missed something.
Currently when you go to https;//myserver.com/owa you get met with popup login prompt when you should be getting forms login.
When you look in EMC, under server configuration, client access, there is nothing listed for OWA.
I am attaching screen shots of the CA tab of EMC, the 404 error you get when you go to myserver.com/owa and the 501/505 error you get when you go to myserver.com/owa/default.a
The last thing i noticed which seemed off to me, is that in IIS under the properties for the OWA virtual directory, under configuration there was nothing listed under Application Extensions. When i went to add the .owa extension and browse for the needed DLL, it was not listed in the most recent versions directory. The only place that i could find it is under the original v2.0.50727 folder.