I’m developing on SQL Server 2012 Enterprise, and I have a problem. When I access “Reporting Services Configuration Manager” the Report Service Status shows Started, but if I go to the Report Manager URL http://<my computer name>/Reports sometimes when I restart the computer I get a log in dialog and then the SSRS is working fine but sometimes I get this:

I tried different browsers, restarting the SSRS service but nothing seems to help any ideas?
I found the solution, it appears that Skype was using the 80 port that the SSRS was trying to use and that prevented me from entering the report service.
You need to edit Skype settings go to Tools->Options->Advanced->Connection and uncheck the “Use port 80 and 443 as alternatives for incoming connections”
and that fixes everything 🙂