The TCP/IP connection does not closed after a VISA close

I am using the VISA functions to communicate with a Sorenson SGA power supply from a Windows XP computer.  I have the VISA TCPIP Resource defined in MAX and use this alias name in the VISAResourceName for the input to the VISA Open.  Then I write a SCPI command, such as *IDN?, and read the repsonse.  Then I close the VISA session.  When I look at the TCP statistics using the netstat -n command, I get the following response:
Proto           Local Address                 Foreign Address    State
TCP            10.10.10.9:3881              10.10.10.1:111       TIME_WAIT
TCP            10.10.10.9:3882              10.10.10.1:111       TIME_WAIT
 
If I query the ID again, I get 2 more TCP connections with different local ports numbers.  Every time I perform the query, I get 2 more TCP port connections at different local ports.  It takes about 1 minute for the TIME_WAIT's to time out.  If I query the Sorenson enough, I can fill up my allowable local port connections.
 
1)  Why doesn't the TCP connections go away after the VISA Close?
2) Should I be opening and closing the VISA session every time I want to talk to the Sorenson?
3) What does the VISAResourceName control or constant actual do to resolve the alias into a IP?
 
This Sorenson power supply does not seem to be very quick to repsond to TCP requests.  If I set the timeout on the VISA Open to anything less the 100ms, I cannot get a session open every time.  It will fail about 50% of the time.
 
Has anyone had experince talking to the Sorenson power Supplies using VISA TCPIP?
Thanks,
Julia
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