If you try to use Msg.exe to send messages from the command line on an administrative workstation running Windows 7 to a server running Windows Server 2008 in the same domain, you may get an "Error 5" or some other error message. You can get Msg.exe to work on Windows 7 by doing the following:
Use Registry Editor to configure the following registry entry:
Key: HKLM\SYSTEM\CurrentControlSet\Control\Terminal Server
Value: change from 0 to 1
Then reboot the Windows 7 computer and now Msg.exe should work provided that the account you are logged on with on your Windows 7 computer has administrative privileges on the remote server.