Avanti blocks Windows shutdown and sign-out to avoid inadvertently crashing an Avanti instance.  If a local Avanti instance is running when a Windows user attempts to log out, or if Avanti is running anywhere when a Windows shutdown is issued, the logout/shutdown process will pause and a "The following applications block Windows shutdown" message is issued.

Warning:Terminating an Avanti instance without first shutting down the O/S is equivalent to pulling the plug on a legacy Alpha server.