Funniest thing... I have WP 3.5.1 up and running and it works great. I am able to log on to my dashboard through the Admin login page. However, I just found out that if I click on any Theme's Customize link or Live Preview link it takes me to the page where you see the themes attributes in the left-hand column and WP asks you to log in again as the Admin.
Here's the strange thing, I typed in my password, for brief second I see that it says I have successfully logged in and then the page seems to reboot itself and go back to the Admin login page and displays an error that I have not successfully logged in.
Everything else seems to work fine, I just can't customize any theme or even live preview it because of this login loop. Any suggestions?