Have you ever heard of this happening with PDF creations?
Found error between XP Pro 32 bit to XP Pro 64 bit Adobe PDF settings. Somehow the "A0" page size changes to reflect the "ISO B2" size page when using the page setups within ADT2006. The half size A2 Page setups work fine. As a work around I created a variation of the "Page Setups.dwg" and renamed it to "Page Setups 64b.dwg" and redefined the setup to reflect the needed page size.
Any idea what may be happening?