Invisable Guards in Caladon.

I did a search and did get any results, so I hope I'm not posting something that's already been posted.

A couple of times in Caladon, when I'm about to go to the first murder scene location, I've been attacked by an invisable guard. Like, I'm attacked by something I can't see, but If I scroll over where the attacks are coming from it gives the stats for guard.

This would be fine, but it causes all the other guards to attack me.

Does any know what this is about? :-?