Today I ran into a strange problem. I was working on the Central Administration (CA) of SharePoint Server 2010. I was planning to manage some system settings (manage servers in this farm). To my surprise I got a 'Access Denied' message.
After searching around for a while, some reboots, changing authorization settings in the web.config I found the solution. I made a bookmark inside IE to navigate to the CA. I started just IE and clicked on this bookmark. And thats not good!
You need to run Internet Explorer explicit in administrator mode to get full access to all options inside SharePoint's CA.
It seems that is has something to do with UAC.