TCP/IP has reached the security limit imposed on the number of concurrent TCP connect attempts.
Windows XP with SP2 installed limits the number of simultaneous outgoing TCP connections to slow down the potential spread of worms, viruses etc.. Unfortunately this can also affect scanning and monitoring programs like the EventSentry heartbeat monitor.
For more information on how to change or remove this limit visit http://www.lvllord.de/.
Additionally, you can adjust various aspects of the Windows TCP stack in the following registry key:
Some of the registry values worth adjusting are:
TcpNumConnections: Maximum number of connections TCP has open at any given time
TcpTimedWaitDelay: Amount of time a connection remains in the TIME_WAIT state
You can find out more about these and other related configuration values by searching at http://technet.microsoft.com or your search engine.