Lately I've been seeing more and more pop up ads making it through FireFox. It seems like all of the major ad networks are using this workaround now. FireFox actually has a built in way of stopping this that has been disabled by default for some reason. If you'd like to enable it

1.) In the FF address bar type about:config
2.) Right click on the page displayed and hit new --> Integer
3.) Put privacy.popups.disable_from_plugins in the first box and 2 in the second box.

There are 3 possible settings for this.

• 0 is the default and allows them all.
• 1 Will treat these windows as a popup but not block them all
• 2 is what we want since it will block them all.

If you're still having problems with this give the adblock extension a try.