redsn0w, you shouldn't sign messages with simple vague phrases like I'm redsn0w, anyone can copy that and use it at any point in the future to pretend they are you. Particularly bad in this instance since it's a vanity address. You should include something unique to the situation you are signing the message for, such as today's date at least.
Yes you are right , I've posted a new one :
https://bitcointalk.org/index.php?action=profile;u=147832 can you help me to resolve this inconvenient?
Good point. I have edited my original message where I included his sig. Redsn0w, you should probably edit your message where you quoted me.
Done , thanks for the help. I know someone is trying to ruin my reputation , but I don't know why.
This does not really solve the issue, I still have a signed copy of you message "I'm redsn0w." (I would ofcause never misuse this), but others (scammers) might have a copy as well.
I recommend that you start working on a new vanity addy, you have unfortunally spoiled the one one you have (imo).
No hate from here, I understand that you make mistake in a stressed situation, it is natural.