To start a DISABLED Messenger service on Windows Server 2003, either type the following commands, pressing Enter after each line:

CD /D %SystemRoot%\system32                              sc.exe config Messenger start= auto                              net.exe start Messenger
You can also run the StartMessenger.bat file, which contains:
@echo off                              %SystemRoot%\system32\sc.exe config Messenger start= auto                              %SystemRoot%\system32\net.exe start Messenger