Question:- Does you application modify general.useragent.vendor or general.useragent.user? I am playing around trying to find a more up to date agent setting that will work on facebook. I have discovered that they only work if put in general.useragent.vendor. This is, of course, reset back to original on browser restart. If you define the agent in general.useragent.user, facebook starts to load but does not complete. Why do I want to change it? To stop that annoying "update you browser" message that facebook comes out with from time to time..