what in the world is going on here?

I have 2 mixed breed Siamese cats...from a Calico grand mother. They are "Bert & Ernie". They are 7 years old. For as long as we have had them they have been indoor anf outdoor kitties.... spending almost all day lounging up stairs on our bed, and sneaking out into thier world at night and returning before dawn..... They go out our bedroom window on the second floor. We have a ladder there for them. We have also had 3 dogs and recently had to put 2 of them to sleep within the last 2 years.. we still have one left Sadie, a mixed breed Cocker... she is 13 and deaf....
Here is the mystery..... About 2 months ago Bert & Ernie stopped coming in the house!!!!! At first we thought it was because it was hot & humid and they were seeking relief under leafy foliage... but on some days we noticed them actually sleeping in the driveway dirt... with their noses actually pressed to the ground???? What is that all about? We manage to coax them in once in awhile, but that lasts about 3 or 4 minutes...and they are crying to get out.... if we refuse to let them out, they go flying up the stairs and down the hall and out the window like a bat outta hell!!!! Good Grief! I don't know what is with them!.... Bert has actually taken to sleeping in the front yard in the grass... He will hardly come in at all... Ernie comes in to get his ears rubbed and then he is gone. We have shut the window, but they drive us crazy crying and constantly walking under our feet and running for the door every chance they get.

My husband and I are totally baffled by this behavior... nothing has changed in our house that we know of.... anybody have ANY ideas?

Any new neighbor animals?? My Zoey was visiting next door

I might be totally off, but this happened to my dog when I was younger. We had to have the kittens our cat had abandoned in the barn put down. ( i was a child, i couldn't have had the cat spayed)
the dog suddenly refused to come anywhere near the house. Had a friend of ours suggest that the dog knew the kittens went with us and never came back, so he became afraid to come in the house incase we trapped him, took him away and never came back.

I'm not sure if this would be something the cats might associate with being in the house or not. Just a thought.

Perhaps they are waiting for their canine buds to return? You said you had to put two dogs to sleep.

If they are allowed outside, that is where they feel the most comfortable. That is where they are supposed to be (in nature). But it isn't safe for them to be outside, unless you understand what the risks are and accept that they want to be outdoors now.

Believe me I do know the dangers of being outside... that is why this upsets me so much... we live in the Adirondacks ...upstate NY, and there are lots of critters out there that I don't want around my "boys".... I also know that natrually they love the outside, we always let them go out or in...they did each about 50-50 of their time.... but now they are out 98% of the time... I have had them for 7 years, and this has never happened... Outside is not a new thing for them.

Have they been neutered? If they are not neutered, or were there was even a little bit of testicular tissue left behind, this is also a possibility of why they don't want to come in. When I was a kid we had a male cat who was neutered, (turns out not all the tissue was taken) and after a few years he started to wander off and began spraying his territories just like an unaltered male. He only came in to eat, never wanted to come in, sometimes days at a time. Check with the vet either way just to make sure everything is okay.

Yes ... they are both neutered... We did it early when they were young...