Error 5104 "SRV_TIMEOUT" with SOAP 3.0   

Hi
I developed a webapp who works with SOAP Toolkit 3.0
It works good but with some customers that use an ISA server,
after about 2 minutes my webapp stop with the error 5104.

Why?

date: Thu, 11 May 2006 06:02:02 -0700   author:   Alessandro