I think the problem is in the Cookies. The Privacy tab in Options won't open. I'll do some searching and try to see why it won't open.
EDIT:It was one of the add-ons that was blocking the tab, however it still won't work. This is what I get now.
A critical error has occurred.
Failed to load viewstate. The control tree into which viewstate is being loaded must match the control tree that was used to save viewstate during the previous request. For example, when adding controls dynamically, the controls added during a post-back must match the type and position of the controls added during the initial request.
EDIT:Got it. I cleared the cookies and restarted the tab and I was able to login.