Remote control another user's session

Here are web pages that show you how to establish a remote control session with a customer's server.  Choose the web page right for the customer's version of Windows.

Windows 2003:  https://technet.microsoft.com/en-us/library/cc738832(v=ws.10).aspx

Windows 2008 R2: https://technet.microsoft.com/en-us/library/cc771538.aspx

Windows 2012 does not support Remote Control or Shadow sessions.

Windows 2012 R2:  It isn't connected with the task manager any more.  See this article for how to find it and make it work: 

http://microsoftplatform.blogspot.com/2013/07/detailed-walkthrough-on-remote-control.html

Here is the official 2012 R2 Microsoft page but it isn't as good as the one above.  

https://technet.microsoft.com/en-us/library/cc725700.aspx