For the past several months now, when I log into CM, I type in my email and password and hit enter. The page reappears blank and I must enter the identifying information again. Then I'm logged in. This happens more than half of the time. I've noticed that it occurs most often when I log in from a computer after I'd been on CM on a different computer (home / work, etc.).
Why does this happen? Is it a glitch, or some security measure?