If a warrior uses the spell vengeance, and dies before the duration is over, and clicks to respawn at a starting point in structured pvp (or even WvWvW zones) the spell continues to exist on your character, and kills him again shortly after the duration is over.
Sometimes, it wont allow you to respawn after this, and you have to re-log entirely, or if using a siege weapon, you will be permanently stuck in the siege weapon control interface and unable to control your character.