Yeah. I forgot that the validation routines use that set of data, and failed to notice the validation error when I tested the change.
The fix is to remove line 652 of cp2_vars.cgi.
*edit* Filed as bug 9401.
If anyone's experiencing this bug and would like it fixed, please open up a support ticket
, and I'll update your site. You must enter your FTP and admin information in the ticket. I am not going to mail the file.