I had the same problem in chapter I when I played the citywatch mission..umm..I donīt remember the name but it had something to do with the Luskan ship entering Neverwinter docks...Anyway, I just reloaded it time after time until the man "wasnīt busy" anymore

You may also want to try not to cast any great magic blasts like fireballs or fire walls when you know that the battle is going to end soon ( I kept my party members far away so that they couldnīt do any damage to the enemy). Itīs a bad bug. Hope you can get on!