Talvez você possa tentar criar um novo valor DWORD (no caminho já mencionado) e ver se funciona?
Windows Server 2003 "oferece dois métodos de controle TIME-WAIT
The TcpTimedWaitDelay registry value under the HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters key can be used to alter the default setting. Windows Server 2003 TCP/IP allows this value to be set as low as 30 seconds, which should not cause problems in most environments, or as high as 300 seconds. The number of user-accessible ephemeral ports that can be used as sources for outbound connections can be configured using the MaxUserPorts registry value, also found under the HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters key. By default, when an application requests any socket from the system to use for an outbound call, a port numbered between 1024 and 5000 is supplied. MaxUserPorts can be used to set the value of the uppermost port that the administrator chooses to allow for outbound connections. For instance, setting this value to 10,000 (decimal) makes approximately 9000 user ports available for outbound connections. For more details on this concept, see RFC 793: Transmission Control Protocol DARPA Internet Program Protocol Specification. Se você pudesse fazer isso no Windows Server 2003, certamente você pode conseguir isso no Windows 7 Enterprise? (Ou até mesmo o servidor de 2008). O único problema é que não consigo encontrar nada sobre como alterar a variável de tempo de espera em qualquer sistema operacional na Internet. Um de seus superusuários pode me ajudar?