If you install Reporting Services on Windows Server 2008 (RTM or R2) and attempt to verify the installation by opening the http://SERVER/ReportServer site, you may well see the following message:
Reporting Services Error --------------------------------------------------------------------------------The permissions granted to user ‘MCGEOWN\Sam.McGeown’ are insufficient for performing this operation. (rsAccessDenied) Get Online Help
SQL Server Reporting Services
Additionally, you may be able to access the http://SERVER/Reports site, but will have no permissions:
You may also spend a good while checking DB permissions, IIS configurations, file permissions and so on. And after all that, you may just stumble upon the fact that if you run Internet Explorer as Administrator, it will work as expected.