Our environment is an N-Tier architecture, with a data-entry client
application
that is used all over the country.  The client application uses HTTP
and the
MS Winsock control to get the data back to the central SQL Server.
The application was built using VB 6.0

We are using a Winsock server application that interfaces to MTS for
the data layer. Essentially, the configuration is as follows:
Client ---> Winsock ---> MTS  ---> SQL Server 2000.  
All of theses components are on separate Windows 2000 Server machines,
with the exception of the client's machine.

The problem occurs on the Winsock application.  It is an error that is
returned from the MTS component (Run-Time error 3021: BOF or EOF has
occurred).  We understand the nature of this error and its causes.
The error, which is not occurring in a consistent manner causes the
Winsock application to hang until a user clicks through the error
message and then restarts the server app.

We have determined to some extent where in the code the problem is
happening, but no pattern has yet been established.  We also noted
that the client that causes the Winsock app to fail, could turn right
around and send the same data with no problems what so ever.

This error has been occurring on average of once per week over the
lifetime of the application, which is roughly 18 months.  Recently we
needed to upgrade our firewall software to Symantec's Raptor 7.0.
Previously, we used version 6.0.  This upgrade caused the error to
occur almost every half-hour.  In addition, the previous firewall
(6.0) software was on a NT 4.0 environment.  We installed Symantec's
7.0 version on a Windows 2000 Server.

Unfortunately, we are unable to duplicate the problem in a testing
environment,
and we cannot replicate the amount of load that is coming in from our
clients
over the internet, as we have limited resources to create such a load.

If anyone has any insight to this particular scenario, your help would
be greatly appreciated.