#1 - Nov. 6, 2011, 6:13 p.m.
When in a party and a boss battle is triggered, the window comes up and asks if you want to accept. When everybody but one person accepts, the last person to accept's button order changes. It changes from Accept/Cancel to Cancel/Accept. This can cause a party member to Cancel instead of Accepting like they mean to.
This happened to both me and my other party member and he had to complete the boss battle alone.