Are you able to browse the memcards from the PS2 browser? what about any other games? is this happening to MVC2 only? if it’s happening to every single game and at the PS2 browser then the port is probably dying.
it could be that mvc2 for ps2 makes the system angry. I would be pissed if you shoved that version in me. Seriously though I had the same issue but only on p1 side card and only that game but I never questioned it and just used p2 side. Did you try the third slot?