I deal with a lot of pages that aren't standards compliant and have to be rendered in IE, so my "default browser" is a tiny app that examines each URL and sends some to IE and the rest to Firefox. Every time there's a new version of firefox, it makes itself the "default browser" and now all of my non-compliant pages try to open in firefox, so I have to dig into the windows settings once again and tell it to use my app to open HTML documents. The "Always check to see if firefox is the default browser at startup" is not checked. This happens each time a new version comes out, and has been happening for over a year.