Windows 7 forum: Ability of java portlet to pass params tied to windows user

We have a we web based application that accepts URL queries to pull up images from the server. Most customers use the get method and URL will look something like http://server/applicationpage.aspx?param1=123¶m2=456. But the application will also accept a POST request.
We have a customer who uses a POST request and has some sort of Java portlet (developed by another vendor) that generates the URL request. When logged into windows with user A, the parameters are passed correctly as a POST request and image opens normally. When logged into the same computer as user B, just the http://server/applicationpage.aspx is passed via GET and no parameters are passed.

When the user tries to launch the image in either case it opens a portlet generated page which launches the URL for our application. For either user A or B if you view the source for the page it is the same. It shows and <nload submit form call and then the form contains the link to our page with all of the valid parameter names and values for the specific image that is to be requested. For user A they are successfully passed and for user B none of the parameters are passed (neither name or value) to our page - it just launches the application page with no parameters. For user B, if we copy the source for the portlet page launched by user B, to a text file and rename it to html, it will launch the image correctly.

This is occurring with Windows 7 and IE8. We have tried resetting IE settings to default and making sure Java was enabled in the browser and disabling all other IE add-ons. Originally user A was admin and user B was not. During testing user B was also made admin (IE settings were reset), but this did not resolve the issue.

Does anyone have any suggestions for settings related to the windows user or ie profile that might be causing this behavior?