I try to register using my call (F1CHF) without succes.
So I have done with another name and email, it's ok ...
Could you destroy F1CHF user and F1CHF@free.fr in the database
after that I will update this profile (email and so on ..)
I think that the Forum did not let you use F1CHF because it already had the "FRANCOIS F1CHF" name in the database since 2011, and the duplicate search found the string F1CHF.
There does not seem to be an F1CHF user, and the F1CHF@free.fr e-mail address is not in the database, so you should be able to change that.
Let me know how you get on