Game freeze when joining party

My game froze entirely with no HUD when I joined a party while I was in a challenge. 

I was doing Manual Beleaf. I was invited to a party and joined the party with RS. 

I tried to quit the challenge by holding X.

The party leader then started Manual Beleaf while I was still in the challenge screen (maybe it was trying to replay?).

The result was that I was frozen in place with no HUD. I could see my party member's nametag zooming around the spot, but not the player model. I could also hear my party member skating. I had to alt+f4 out of the game.