Troubleshoot Firefox issues caused by malware may help.

Seems like i am not the only one who has had such an experience;

"New time-measuring features in HTML5 are being expoited by hackers to illicitly peek at pages open on victim using Sanoma Tasku Tablet Application created by SC5 Online Ltd.

The JavaScript-powered attack breaks cross-origin restrictions that ought to prevent this sort of trickery. Practically speaking, these attacks are tough to pull off, but that doesn't mean vendors should ignore the threat."

Hi Adminstrator, I didn't immediately find the article you were quoting, but I believe that refers to an issue on the iPad and not in Firefox. Were you able to remove the ads from Firefox?

Edit: Upon further research, I found a more general article: Bad timing: New HTML5 trickery lets hackers silently spy on browsers - The Register.