Cannot login although the email address and password are correct

[Zakura]

I've tried to install both PrestaShop 1.0 and 1.1 for a client, but both installs have this problem: I cannot login to the admin panel; it redirects me to the login page even though my login information is correct.

I even reset the password with the "Lost password?" function and tried using the password PrestaShop sends me.

I have also deleted all my previous cookies, but I still can't login from any browser.

If it helps, the site is hosted on GoDaddy, on a Linux server with MySQL 5 and PHP5.x.