Why wont my passwords/screen names stay saved/open??

[Cannonfury]

Usually when I go to yahoo.com, POF, my other e-mails, social networking sites....etc I don't have to log in, they are already logged in for me. But now every time I go to one of these sites they ask for my screen names and passwords. No matter how many times I click the box that says "stay logged in" or "remeber password/screen name" it wont keep it. What is wrong???


Does turning my computer off simply by turning off the power strip that its all plugged too, have anything to do with it? I do that cause sometimes when I press Turn Off computer, or shut down...it wont shut down.