Did you determine what this was? I've noted a few myself. I halfway suspect users attempting to validate membership using broken URL's. Some e-mail programs break those long confirmation URL's into two lines and users can't seem to grasp the concept of grabbing the entire string. Have added a comment about this to the validation e-mail, but there will always be some who can't fit the square block into the round hole.

That's just my guess.

How about this one, "URL Forwarding"? Is there an ability to e-mail a thread or url via the board to someone? I haven't stumbled across it yet if there is.