Sims won't go through doors or gates.

I just recently got Sims 3 Supernatural. I played it without glitches for a few weeks, and then last night, none of my sims could go through my outside doors or gates. They all get the symbol with the footprints and a red line through them above their head, as if something is blocking their pathway. I keep buying new doors and gates, deleting walls and fences and starting over, but they still can't get into or out of the house/garden. I keep having to teleport them places, which is a pain. Any ideas??