Missions not working, stuck in a loop.

When I take any mission (as of today), I cannot complete it. At some point during the mission, when I click to go to the next page, a Yellow mission box does pop up, but it is the same box as the first page, and clicking next starts the mission over.. and it goes in a loop. If I close the box and wander away from the site, it will keep on randomly popping up on an site to get me to continue the unending mission, causing me to restart firefox.