cannot change password

I somehow forgot my account password, and used the Get new password feature. I received a link to reset the password, and when I click on it I get this error:

Not Acceptable

An appropriate representation of the requested resource /blog/wp-login.php could not be found on this server.

Of course, the file is there. If I cut the ‘key’ argument and leave only the ‘action’ argument in the link, it finds it. I looked into the database, and the user has the ‘user_activation_key’ field set to the key received in the link.

Any ideas how to make this work? Thank you very much.