I have solved a "bug" in Firefox 3.6.8.

The bug : When I was in a web site like a banking site for example, many windows were opened while surfing in the web site. When I disconnected my personnal space, a new window was opened but an active window kept opened. I really felt a security problem.

How to solve : You must uninstall Firefox and re-install it. I precise that Firefox was pre-installed when I decided to install Linux Mint.

Then, I thaught it was a Linux way to use Firefox but in fact it probably was a bug. So Firefox stays my favorite web browser.