I had the house in Falkreath all finished and moved my Child there, i brought Mekko over not long after.

Now anytime i go inside the Main Hall the game freezes.... Dog's messing up my game.

I doubt it is Meeko causing the freezing, did you disable all the workbenches? Having Serana as a follower at Lakeview manor has been known to cause problems, or did you build the greenhouse perhaps and it is causing the problems. Meeko might cause problems in the house but freezing should not be one of them, ask him to follow you and take him outside to guard the chickens, just tell him to wait near the animal pen.