I don't know why lot's of people have problems like that, i use Safari, Google chrome , IE and never ever had a problem, i am always logged in.(well, when i double click to enter GG i don't have to log in, that's what i 'm saying.)
I don't usually have to login. I wonder if your computer updates has the box clicked to delete password memory while it performs its "behind the scenes" tune-ups? I'm sure it has a better technical name. I am by no means a wiz but I remember seeing this option in the advanced tab in one of the windows of my computer system. I