I was checking out the recent upgrade to 2010 from 2003 and I noticed the following in the eventlog:

Sender Information: System.ServiceModel.ServiceHostingEnvironment+HostingManager/42194754
Exception: System.ServiceModel.ServiceActivationException: The service ‘/Autodiscover/Autodiscover.xml’ cannot be activated due to an exception during compilation. The exception message is: Could not find a base address that matches scheme http for the endpoint with binding CustomBinding. Registered base address schemes are [https].. —> System.InvalidOperationException: Could not find a base address that matches scheme http for the endpoint with binding CustomBinding. Registered base address schemes are [https].

This was popping up mostly when someone was logging into OWA for the webmail access, but it also showed up a slightly different way when someone would try to reserve resources (rooms) for meetings.

And here’s the easy fix for me:

remove IIS binding http 80 127.0.0.1
remove IIS binding https 443 127.0.0.1

This might not apply to you, but just make sure you only have ONE binding for each port (80 and 443) and the best practice is to have it bind to any (*)