nothing to be alarmed at but i'll look into it.. it may be as simple as BrowserTraySwitch using the short version of a filename and firefox comparing the registry entry with the long version of its name, etc.
there is no "standard" way for a browser to indicate that it is the default browser, so all browsers have slightly different ways of checking if they *think* they are the default browser. it's a real mess. thank you bill gates.