i had this same problem, but its an easy fix. go to
swapmagicfix.com and get CDLoader Beta 5.1. burn the .bin file to a cd using nero or such and follow these steps during booting (assuming you have slide card or similar method):
boot swap magic cd version
swap it for CDloader(with flip/slide) and press x
once CDloader loads press x
select 5v3 no pn press x
PRESS eject on your ps2
swap for swap magic DVD version
once it is recognized in the bottom left hand corner press x
it will instruct you to swap with dvdr. use your flip top or slide card to swap the disc with the backup.
press x
good luck