I'm not sure how to reconfigure it. Clearing the cache didn't help. I am assuming because I am behind a corporate firewall, what I can't see in IE8 would be the same as what I can't see behind Firefox 7.0.1. That being said, I opened a URL (public) that I created or ArcGIS Explorer online in IE8 and in Firefox 7.0.1 and it's fine in IE8, but asks for a password in Firefox 7.0.1. The strange part is that I am logged in with my ESRI account in Firefox, but not in IE8. Also, I still get a blank page when going to the main ArcGIS online page. I have the most recent version of Silverlight installed, so I'm not sure what's really going on.