There's a quest from Captain Falron (Caer Ulfwych - Salisbury Plains) "Curbing The Ogre Presence" where you need to kill 10 ogre warlords or berserkers. After killing these 10 mobs Captain Falron just thanks you and gives no reward xp and quest stucks in Quest Journal (you have to manually delete quest). Did this quest like 3 times - no reward.