Nearly corrupted...

[Sage]

Yeah, it was a close call... I was almost corrupted by someone named JOKER, someone who used to be a friend of mine. I just need help on what to do, cuz everytime I go somewhere, JOKER's right there, counting down from 3,2,1, then eventually 0... I reseted the game when JOKER reached 0, cuz I wasn't gonna risk my first memory card of characters. But SonicTeam won't obviously do anything about it.
So I need someone who's smart and can help me on what to do, cuz I can't find this person's card anywhere in my GC list(had to go offline to check) so this person must've used a different character when I got their GC, so I can't really block them right now. If anyone here knows JOKER, I need the names of their other characters to see that I do have it. And I also need to know if there's a code to unblock yourself from the person that did block you...
I'm really serious, I do not want to lose my 4 characters, then have JOKER poping up continuously if I start a new character. And worse part is that my other characters are in danger too.
Maybe I'm just paranoid about JOKER corrupting me, but I know that he/she threatened to corrupt my character. So in the first place, I need to know if JOKER has an AR or something that can corrupt my character. But I really do need help on this badly, or else its over for me and my days of PSO online...