function implode

warning: implode() [function.implode]: Invalid arguments passed in ... /sites/all/modules/spam/spam.module on line 869.

This is the message I get when I try to save configurations in site configuration/spam/general. It appears to have a spot where I assume I would select what type of content I want the spam filter to work on, but there is nothing in the box. I can change and save my spam filter message, and can change and save my posting action, but all of the possible options still give me the above error message.

The filter doesn't appear to actually be filtering anything out yet, as I'm still getting a ton of really obvious spam. Possibly that's just my settings?

FYI, I'm using drupal 5.7.