PS2 video problems playing PSX game

[Faulty Ground]

Alright guys, Ive got my PS2 (dinosaur edition, not the slim one) which has been working flawlessly since the day I got it. It is connected through a Philips RF modulator to my ancient Zenith System 3 space command. The PS2, cube and xbox all look fine on it, however, when I try and play FFVII (I finally gave into peer pressure, Im going to try it) once I get past the boot screen and it loads the game, I start getting screen jerking, much like one of the really old TV's where the V-Hold is off a bit. It doesnt do it at any other time. I cant say for sure if its all PSX games or just FFVII since I dont actually posses any other PSX games and Im pretty sure I would find my reproductive days at an end if I asked my girlfriend to let me borrow her Wild ARMS. Any ideas?

If anyone is technically inclined to care:
Console: SCPH-39001
Browser: 1.20
CD Player: 1.20
PlayStation Driver: 1.10
DVD Player: 2.12U

UPDATE: Hey wow, problem @#$%^&*!!! solved. I decided to clean the disc with some shoe polish instead of water (white shoe polish is AWESOME with small scratches) and in the process discovered that there is a very tiny crack in the disc. So as I continue to add new adjectives to my 4 letter vocabulary, this isn't an issue anymore.

On the upside, my recabling of the entire bedside entertainment system has rewarded me with a much clearer picture than before.