After a recent Windows Update in December 2014 or January 2015, I now have to run a lot of programs as Administrator in order to avoid access/security errors. I'm not sure why, as I'm a local administrator on my machine. I am running Windows7 x64.
For instance, if I run a Command Prompt without running-as Administrator, and try using "net start" or "net stop" to modify a service, I will get various errors, such as "System error 5 has occurred" or "Access is denied". However, if I open up my Services window, I am able to start and stop the same services without issue. I had always been able to start/stop services from Command Prompt until after a recent reboot. So, either a Group Policy or a Windows Update is at play here.