Hi

I have a pretty serious problem.
I have developed a winforms app that calls a webservice using .NET
Framework 1.1 with C#, IIS 5.1. and SQL Server 2000 server.
After installing the WS, I have installed few client applications.
3 of them are facing a problem that can be easily reproduced as
follows.
The user starts the application and logs-in (authentication against
the WS), then opens a form and work a bit (this means other serveral
calls to the WS. Then, the user stops working with the application
(e.g. gets a cup of coffe, waists some time chatting, sends some e-
mails, etc).
After an arbitrary period of time, the user remembers he/she has to
work and gets back to the application.  We found out later that this
period of time is related (but I could say equal) to Connection
Timeout setting of the web site in IIS (default 900 seconds).
Now comes the bomb. The first call to the WS will freeze. It seems
that the WS receives the request, processes it, but the response never
gets back to the client. In turn, the client will wait forever (or
some huge amount of time) to receive the response. Note that I set the
proxy that connects to the WS to wait forever because the client may
initiate some calls that may take hours.
Only 3 installed machines are affected by this problem. Others work
fine.
Client machines run on XP, the server machine runs on Win2003 server.
I kow for sure that the 3 problematic machins have NOD32 installed.
Don't know others.

Any idea?
Thanks