In Windows Server 2008R2 Microsoft introduced Session-0 security – easy explanation: so it becomes much harder for interactive service to run as Local System and interacts with users.
If you want to run EA (an interactive app) as an unattended Windows Service (as an interactive service) you have to do some strange steps to achieve. Follow the Version 1.0 of the attached whitepaper to get it run.
Oh yeah, that is fun
Whitepaper: EA as unattended Windows Service