"Invalid key!" when i try to login

Hi everybody,
im running a blog on my site thejoe.it with wordpress since 2010. I’ve always updated it, and today my wp version is 4.1.1. It’s been a while since i have posted my last article and today i wanted to post something new.
When i try to login i get an “invalid key” error.
I tried to look for a solution on the forum and over the internet, but noone running recent versions seems to have the same issue.
I have tried to reset my password both via the reset password page and managing the database, both cases with success, but as soon as i try to login i still get the “invalid key” page (in the URL i see “wp-login.php?action=invalidkey”).
I’m also using the plugin “wp login security alert” that checks if you already logged in from the IP you’re using and if it’s an unknown IP it sends you an email with a link to autorize the IP (so if it wasn’t you the IP won’t get autorized).
Just for information… I’m able to access the database and wp files.

Anyone has ideas?