Hmmm my friend had the same problem
If the problem is not one of whut those awesome people suggested above,did they fully activated their account during the time the registractions were opened?Maybe they need to re-activate idk
o_o Because I've heard this problem again,maybe something like that happened,if they re-tried that and that was not the problem he should of been contacting an admin o-o ?
or did they have other accounts on the same e-mail?Maybe their account got deleted cause of that
idk ;n; I dunnot think it is really a problem if they do not login into their forums ^^ but I am not an expert so I can't give an 100% correct answer aboot it ;u;