There was a thread on this last week.. seems its pretty common.. some just kept trying till they werent, otheres restarted game and it worked fine.. while others said it was due to having negative relations wth that lord/companion.
I had it happen to me once.. once I restarted game hasent happened again... mine went a bit more then that.. the whole city went hostile on each other.. the Castguard killed everyone in the city (Armor merchant/guild master ect..) before i even went into the dungeon.. came out and he would help me kill but i was trying to rescue 6 companions and they would all attack me,.. so.. happens.. try restarting game.. let them rot.. or just keep trying..