OK, this is a tough one. I saw it as a kid in the theater in the mid to late 70's. I don't remember much, it was a bit of a "B" movie. Anyway, here's the details I do remember: A grandpa type character has built a modern architecture type house in the desert (american south west I think) and the family comes to vacation/visit. I think they and the house slips through to some other reality or something. I vaguely recall UFO type stuff. Not a scary movie so much as a "mysterious world we live in" type of vibe. I think everyone survives the film. If it helps, I don't remember the cast having any non-american accents. And that's about it. I know it's not any of the House movies, though House 2 had some similar themes. Definitely a movie and not a tv show, again the old Otherworld series comes to mind, but about a decade too late. Anyway, if this sounds familiar at all, please make a suggestion. Thanks! Any help would be appreciated.