Users of my website are complaining about a popup box which appears repeatedly and requests them to enter their username and password. This is on a page which does not require any login to access. I've seen the popup myself and verified it only appears when using a Firefox browser. The versions I've seen the popup on are all 3.0 or higher. If you click ok or cancel the popup box disappears, but it comes right back no matter how many times you try to get rid of it. I've seen this same problem on multiple computers running different operating systems.