Since I downloaded the last Firefox version 3.6 15, no matter where I am, I am back in my homepage and I get the message "The URL is not valid and cannot be loaded", usually I can go back to the site I was in and keep doing whatever I was doing, but often it will happen again. This is happening in both my computer, laptop and desktop, one has windows XP, the other one has windows 7. Suggestions? It is becoming a nuisance being moved from the tab I am, and kicked back to the homepage tab