Security a problem for all browsers
Although I use Firefox almost exclusively at home it is worth reminding people that although pretty secure, no bit of software accessing a public network is invulnerable. No matter how clever Firefox may be, it's ultimately down to the common sense of the user to avoid obvious hazards - hazards that aren't always obvious to Harry Homeowner. I;ve always thought the ease at which extensions can be installed, the fact that unsigned extensions can be accepted would inevitably be a source of trouble. By default Firefox should reject all unsigned extensions and those that don't use SSL. Perhaps it could be extensions could be run in a sandbox environment - at the minute releasing a maliciously designed extension would hardly be a work of genius.