[Eloy]

Check the value type your column 'hp'. If its Float, change especifier here

PHP Code:

format(query, sizeof(query), "INSERT INTO `accounts` (`Username`, `Senha`, `IP`, `hp`, `playerlskin`) VALUES ('%s', '%s', '%s', '%i', '%i')"
                , GetName(playerid), pInfo[playerid][pSenha], ip, vidainicial, skininicial);
            mysql_query(ConnectMYSQL,query); 


to

PHP Code:

format(query, sizeof(query), "INSERT INTO `accounts` (`Username`, `Senha`, `IP`, `hp`, `playerlskin`) VALUES ('%e', '%s', '%s', '%f', '%i')"
                , GetName(playerid), pInfo[playerid][pSenha], ip, vidainicial, skininicial);
            mysql_query(ConnectMYSQL,query); 


Remember

%s = strings
%e = Strings anti injection sql
%f = Point Float
%d = Integer
%i = Ingeger