I had that happen earlier. I think it was software embedded in one of the ads. It jammed my browser tabs and even the keyboard. Finally, I just swiped away the app. When I reloaded it, all the CCF tabs reloaded, and everything was completely normal.
I have noticed lately that when I go to the post reply box, sometimes the ads interfere with my typing. Whenever that happens, I just reload the page, and the problem disappears.