Problem accessing dashboard / logging in

Hello.

Yesterday, I upgraded to WP 3.0 and saw no problems. After that I finally converted most of my categories to tags, and installed the Tag Dropdown Widget plugin to get rid of the ugly tag cloud. Everything seemed to be working fine.

However, as of this morning I can’t access my admin panel. http://otakunvirka.fi/wp-admin/ doesn’t redirect to the login page; trying to login directly from http://otakunvirka.fi/wp-login.php similarly doesn’t redirect me anywhere. I tried removing the Tag Dropdown Widget, but it did nothing. The blog itself displays fine, as you can see.

Any idea where my problem might lie?