I also had this bug happened with no save game anywhere remotely close to this area. I went downstairs, had the encounter, killed all of the golems. I did notice a golem attacking one of the guards so i killed it. Now when I go upstairs everyone is agro. Meanwhile downstairs nobody is agro'd on me. I do notice however that the guard the golem attacks if I mouse over him the default state is for my party to attack him. So it seems as though the golem attacking this guard causes this issue. I am pretty much screwed now until this is fixed... I have attached a screenshot of the broken guard. Also of note, if you kill this guard, another one just spawns in it's place that is friendly
http://i.imgur.com/TnpdTMC.jpg