I've been using Firefox for several years and just ran across a problem within the past two weeks. I usually have several tabs open at the same time while browsing the Internet. Suddenly, when I tried to open a new tab by clicking on the "+" tab at the top right of the screen, a new tab would not open. Then I tried clicking on "file + new tab" and a new tab still won't open. If I click on a link within an email, then a new tab will open, but I cannot choose to open a new tab. Please help! Thanks! :)