Ok, shot in the dark number 32:

In the form that submits the login information, is the ACTION in the form header a full url or just a relative link?

If it is a relative link (e.g. ACTION="login.asp"), change the string to "http://www.somewebsite.com/login.asp" and see if that makes a difference. I wonder if it has something to do the browser control having a problem with the document's location...

MR