We are in trouble with dappling a web database application.

We are in trouble with dappling a web database application.
I have a oracle server(2003 sp1). It run a web application developed
on Visual Studio 2005 using DSR. When user connect from web browser,
it starts w3wp service. Then w3wp start with a few MB memory usage and
star to grow higher and higher. Within few minutes it captures total
memory space (2 GB). Then client fail to get data from the oracle
server. How can I manage w3wp to refresh its memory usage.
we have a test server of 2003 sp1 and oracle server, the web
application as default web site. on the test server we log on with 4
web user, test server works properly, it never more then 790MB memory
of total. even users are idle, memory usage come down to 600 MB or
less.
But on the Main Server which is of 2003 sp1 and a security update and
Oracle server(same as the test server) fail to manage its memory,
start with a few MB and W3WP capture the hole free memory space. When
a single user connect from web browser, it starts w3wp service. Then
w3wp starts with a few MB memory usage and star to grow higher and
higher. Within few minutes it captures total memory space (2 GB). Then
client fail to get data from the oracle server. what can be the cause
of this problem ? what should I do rather then changing machine?