There are plenty of reasons why an administrator could be denied access to the EMS or EMC.
One fairly unique problem that besieged me prevented me from accessing the EMC or EMS. Rebooting didn't fix it either.
After plenty of regular troubleshooting strategies I discovered that the WINHTTPS proxy had been set to something else besides the default and it was preventing me from accessing anything.
netsh winhttp show proxy revealed a proxy was configured, so I ran netsh winhttp reset proxy and then it was fixed! EMC and EMS back online!
Current WinHTTP proxy settings:
Direct access (no proxy server).
Hope this helps someone out there...