Can't login to admin panel – wp-login.php keeps refreshing

So, here goes:

I usually login via bookmark at mysite.com/wp-admin. This morning, i was automatically redirected to wp-login.php. I figured cookies must have expired or something so entered my data and attempted to login.

Nothing happened. I did it again and realised that the login page would keep refreshing without any errors whatsoever.

Tried to login via IE (usually use Chrome) and got the same thing.

The website works fine, no errors appear on it, every page is displayed properly and so on.

I tried every trick in the books:

clear cookies/cache
resetting password
resetting password via phpmyadmin
renaming plugins folder
fresh wp install files
editing .htaccess
scanning website for malware

All operations went through fine, no errors reported. Still, I can’t access my admin panel.

I have upgraded a plugin a couple of days ago, but I’ve posted once yesterday and once the day before and everything went fine. Also checked in once every 4-5 hours and everything went well.

The website is http://autopersonality.com

It is running:

Apache 2.2.19
PHP 5.2.17
MySQL 5.0.92-community-log

Any ideas?