After installing the 4.5.2 then the 4.5.2.SP1 upgrades yesterday, I can not log in to the Admin panel! I enter my username and password, but keeps reloading the login page!
Disregard - I cleared cache and rebooted and this seems to have solved it, however I'm not sure why that would be required. That's never happened before after an upgrade, at least not for me.