Website log in screen keeps refreshing

Hello,

HAve a strange problem. We just went live with NSM (from BM). Everything
went well in cutover except for one internal web site which requires login
credentials. When you supply the credentials and press enter, the screen
just refreshes and brings you back to the login screen. The odd thing is
that this internal site is accessable from the 'outside' via SNAT. When
using the same procedure from the 'outside' you are logged in and can
proceed normaly on the site.

The only way to fix the problem internally is to by-pass the proxy. We
are using HTTP Proxy with SSO.

I'd like to resolve this at the NSM box if possible so we don't have to
visit hundreds of client machines only to type the ip address (of the
server in question) into the connections settings of the browser to
by-pass the proxy.

Any ideas?