My sim's yard has become unroutable, can't reach the door

[schwinnrider]

A most peculiar and distressing event has transpired in my game, as alluded to in the thread title. I first noticed an irregularity at the birthday party. My sim finds parties a bore but decided to invite a few close friends to celebrate his YA->A birthday. When guests arrived I clicked on one and selected 'Invite Everyone Inside.' They all displayed the 'no route' bubble and stayed where they were. That's when I observed an expanse of unroutable terrain blocking access to my front door. I don't know of anything that may have caused it. I moved the door to a blank spot on the wall in the bedroom so I could get in the house without teleporting, but I would be delighted if someone could offer advice or insight on this issue.

[jezzer]

It's been reported off and on since Generations came out.  Search the site.