SOOOO fucking pissed off

Ok, this is the 3rd time I've had this problem, and I am truly enraged now.

My problem is with my favorite game of all time, Xenogears. I play it on my PS2... This is what happened:

I was playing the game as normal, go to save and overwrite my old file. It fails to save, deleting my file in the process...

NOW, it absolutely REFUSES to save, at ALL. Now I'm halfway thru the game, with no save file. It then decides to lock up 5 mins later, utterly destroying any hopes of doing something about it.

I had this problem a few times back in VA, playing it on MY PS2 (playing on my little sister's right now). I was using a different copy of the game, but the same memory card. Figuring it was the memory card, I went out and picked up a new one tonight.

NO DICE. It still refuses to save. I can't figure out WTF the problem is, since every possible fail-point has been tested (Multiple PS2's, multiple copies of the game, and multiple memory cards).

Is there a bug that I don't know about, with the PS2 being faggish about saving to a PS1 memory card or something?

Testing this on other PS1 games as I type this...