Hacking tales of symphonia help

[DarkRising]

I've been playing Tales of Symphonia for nearly 30 hours now and I'm at the end of Disc 1. After the scene with the Mana Cannon, the game is supposed to prompt me to change disks but instead there's only a black screen. I tried changing the discs and inserting Disc 2, but nothing happened. Then, I tried upgrading from theta to both xi, .2, and Neogamma, but the saves I had stored with theta won't register when I boot up the game with them. I really don't want to start all over again as that would take forever so can anyone help me?