Request.form stops working after clicking on page with Integrated

Hello,

I am using asp on a Windows 2003 server, with IIS 6.0, for a large
organization.

I need to collect user names for some pages on the website (which are
restricted to a certain number of users), and am using
request.servervariables(LOGON_USER) to get those names. To do this, I have
turned off "enable anonymous access" and turned on Integrated Windows
authentication for a gateway page (i.e. just for one page in the whole
website).

I can't use Integrated Windows authentication for the whole site because
then some important users who are outside the forest (? or domain??) are
presented with username/password requests, which they aren't under anonymous
access. So, I pre-identify those users by ip address, and steer them around
the gateway page.

The strategy works fine, except for one problem. There is an asp page
elsewhere on the site that requests form variables used in search requests
from another asp page. The requesting asp page works fine until a user
clicks on the page which has Integrated Windows Authentication applied. From
that point on, request.form stops working. There's no error; but all the
results are blank.

Somehow, clicking on the page with the different access permission breaks
request.form until the user closes all instances of the browser (IE 6) and
then starts over.

Does anyone have a suggestion about why this is happening and how I can
solve it?

Many thanks!

P.S. An alternative way to determine the user name would also solve this
for me -- the server is part of a large internal network.