Scenario: Both you and another user are simultaneously logged on to the same Windows 7 computer (this can be accomplished by using the Fast User Switching or FUS feature). You need to forcibly log the other user off from the computer, and to do this you open Task Manager, select the Users tab, select the username of the other user, and click the Logoff button. Instead of the other user's session ending however, a dialog box displays saying "User could not be logged off. Access is denied." What's wrong?
Resolution: You need to run Task Manager elevated. To do this, type "Task Manager" in the Start menu search box, and when Task Manager appears in the search results, right-click on it and select Run As Administrator. Then proceed as previously described above.
Bonus Tip: In case you're interested, the number of users who can simultaneously be logged on interactively to a Windows 7 computer using FUS is limited only by the amount of resources (RAM, pagefile, diskspace) on the computer.
Mitch Tulloch is a seven-time recipient of the Microsoft Most Valuable Professional (MVP) award and widely recognized expert on Windows administration, deployment and virtualization. For more tips by Mitch you can follow him on Twitter or friend him on Facebook.