I read somewhere in a housetraining book that if your dog ever reverts back to going in the house, then they were never fully trained in the first place - you may have thought that he/she was all set, but in reality they really weren't. I am going through the same thing with my pups, so we are going back to square one and taking the time to do it allllllll over again and making sure they master each step along the way before we move on. Giving them too much to master at once is a sure-fire way to have problems, as demonstrated by my little wonders
Someday they'll all get it!