I finally found a copy of this game about a week
ago, after a decade of searching. It seems to work
fine, and everything was going well. Today,
however, it started giving me an odd error:
whenever I save my game, it pops up a
message saying my controller has disconnected.

I am playing on a slim PS2, don't have another PS
system to test on. I've tried other games, and no
such error occurs. I also tried switching
controllers, but the problem persists regardless
(tried two each of PS1 and PS2 controllers).

It's remedied fairly easily, just need to unplug
and reinsert the controller after saving. But it's
an annoyance. Has anyone else encountered such an
issue? Is there a fix?