Whole group thrown out of vet spindleclutch before doing final boss

mad0ni0n

So I used the group finder to get a group for vet spindleclutch. everything was fine we killed Urvan Veleth which is the guy just before the final boss but when we went through the door to the final boss we were all kicked out of the dungeon to the exit door (we couldn't enter again through this door).

Has this happened to anybody else? Is there a reason for this?