Chin Chin Litters The House

We have a beautiful long hair calico, named Chin Chin. She is 8 years old She is one of 3 cats in our household. The problem is she refuses to use the litter. She is peeing and pooping in my dining room, living room and anywhere she can. We placed the litter in the dining room as we thought maybe she did not want to go in the back room where we keep the other litter. She proceeded to poop right beside the box! We have not changed anything in her routine, we use the same litter we have used for years and she has been given a clean bill of health by the vet. We DO NOT want to give her up, but our house smells and we are embarrassed to bring guests into our home because it smells like a huge litter box! Please, help!

Question From: Jen Lyons - Nov 20th 2006