Please keep this browser plugin checker in your bookmark bar at the top of your browser:

http://www.mozilla.com/en-US/plugincheck/

…and click on it right now. There’s a current Adobe Shockwave Flash exploit that affects all browsers around. Please click that bookmark every day, it’s quick, take a few seconds, and you don’t want to spend your time reformatting your computer because some banner ad took over your computer.