I installed a Wordpress plugin called SecureImage that helps protecting against spam by forcing commenters to enter some random numbers and letters, making it harder for spammers to get through. The plugin seems to work fine, but for some reason it won’t work with my customized theme. It works for the first comment, then when the comment poster is recognized, the graphics with the random characters doesn’t appear and you get an error when trying to post. Until I’ve found the reason for this misbehavior, I’ve switched back to the default Wordpress theme.