More specifically Menu Magic II (MM2) and Dreamweaver MX Templates. In DW MX, Macromedia changed how templates work, they got smarter. If you use the Menu Magic II extention kit from Project Seven (PVII), be sure to read this PDF they have written. On a related note, I emailed them about this problem (using MM2 in MX templates) and they got back to me right away with the answer, this technote in their infoBase. Very fast tech support from PVII.
