That happened with one of my dogs too. As a puppy he was always used to being in his crate at night (with the door closed and latched). When he was an adult we decided to give him more freedom and leave him in the room where the crate is, so he can still go in if he wants, but is not locked in. Well that didn't go over very well, he whined and cried and tried to get out of the room and started destroying things in the room. He just felt more comfortable with the routine of being put in his crate. I think it felt safer to him. So we went back to our old routine for a while. Eventually we tried again, but he freaked out again. Then on a day when he had a lot of activity and was really tired, we put him in the crate, closed the door, but didn't latch it. He did push the crate door open at night, but didn't leave the crate. We did that for months. Then again after a busy day, we put him in the crate, but left the door open. He came out and whined a bit, but eventually went back to sleep. Now he's fine being out of his crate for night, but he usually chooses to still sleep in there anyway. I think they just get used to routine and get upset when something is "off".
With your dog, try leaving the house, but stay in the yard or driveway where she can still see you. Then come back in before she gets upset (this may be only a minute or two). Keep practicing that over several weeks, being outside longer and longer. Go out of sight for a minute and then come back. Go out of sight for longer and longer, always coming back before your dog gets upset. Then practice as if you are actually leaving - get your coat, keys, etc. as if you are leaving. See how she does with that. You can then actually leave the yard, but just go around the block and come back. You get the picture. Go slow and let her adjust. She needs to know that it's okay and that you will come back. Also never make a big deal about leaving or coming back. Just quietly leave and when you come back in, just act as if nothing happened at all.