posts NOT saving

I’m having a problem getting posts to save. It doesn’t seem to matter which kind of save I use “save and continue edit” or “save” or “publish”. None of these work on the first try. I have to try to save a post several times. And, of course, I forgot to make a copy of my post before I tried saving it, so an hour of work is wasted. My bad.

So–any ideas on why posts don’t save?

thanks
Karen