Networking is a complex process that requires annoying ways of keeping track of what’s going on. One of the ways to keep track of why a server was shutdown or rebooted in windows 2003 / 2008 is by means of requiring the user to provide a reason for the action before executing the request.
The Shutdown Event Tracker is useful if you run a big network with multiple server or have little control over day to day activities on the server. The opposite happens on a smaller network where usually one person is in charge and the only one responsible for maintenance. In my case I have a test server at home.
To disable the Shutdown Event Tracker go to Start > Run, and type gpedit.msc
On the right pane double click on Computer Configuration > Administrative Templates
Double click on System
Scroll down and search for Display Shutdown Event Tracker and double click on it
Select Disabled, then just click OK
From now on whenever you attempt to shutdown the server no event tracker windows will appear asking you for a reason.