Trying the view an ArcMap Service returns:
"Unable to display map service. Server is not available for service <service name>"
The timeout setting is too short for the spatial server to respond to requests. This is the time that the ArcIMS Application Server waits on an ArcIMS Spatial Server to respond to a client request. Complex maps require a longer timeout setting.
Open the <ArcIMS Installation Directory>/AppServer/AppServer.properties file and change the timeout value.