Not necessarily the disc.

I had the same issue on my ps2, and my ps2 has played most of my other ps1 games with no issue. Played fine on ps1, but I got rid of the PS1, and when I tried to use my ps2 the game would lock up. I think it was on the Dues battle.

I bought a cheap PS1 slim from a friend, and it played the game fine and I could finally get past the boss fight.