Hi Jeroen,

Oh, wow. So I just realized this error is not just the sidebox but it's hitting my registration as well. (Maybe that's a clue about what's wrong?)

Something really seems wrong with my defines. The "newsletter_subscribe_filesnames.php" is in /includes/extra_datafiles/ -- and he "subscribe.php" is in /includes/languages/english/my_template/.

I'm getting an error now on the define "TABLE_SUBSCRIBERS".

Thanks for your help!
Tim