Admins please help. I can't get rid of this "invitation" message every time I use

Hi dear Admins, I hope you can get this problem solved! This invitation comes up everytime I open a new question, or literally any link from When I click on it, it takes me to accept/deny page. Clicking on either one of the options gives an error saying:

Invalid request for accepting/denying invite for ‘CCWC2015’ for team ‘calmninja’.

(because the deadline for the contest has actually ended. That’s fine but the invitation doesn’t go away!!!)

Please help me if you can! It’s really annoying and forcing me to make a new account, thus losing all my points and rank.
the message that I’m seeing