Could not leave party

I joined a party to make a trade, and when I was done I left the party. Only the other persons avatar stayed on the screen as though we were still in a party. I tried to leave again and got the message "this party does not exist", tried inviting someone else to my party and received the same "this party does not exist" error. I had a friend send me an invite which worked, but when I left that party it reverted to the initial bugged party. Finally I restarted my computer completely which seems to have solved the problem.