Firefox 3, which set a one-day record for downloads recently, has been reconfigured in a way that's setting off alarms for webmasters who haven't renewed their SSL certificates. As the US Army just learned, Firefox won't bring up sites with self-assigned and/or expired certificates. At least, not without some extensive hoop-jumping. If you're a merchant you should know that an SSL certificate encrypts data transmissions between two computers. Credit card information, for example, is protected during transmission between those two computers.