Internal Server Error if logging two events in php

Question

I use log4php as a logger library. I don't think this issue is related with that library.

I have following code that is giving internal server error:

  $log->info("Validando datos de registro de usuario: Nombre: "
          . "$nombre, Apellido: $apellido, Usuario: $usuario, "
          . "Email: $email, Email2: $email2");
  $log->info("Lararala");

The curious thing is that the error is not giving in those lines, but after the script, so both events are logged correctly. If I remove the second line, it works:

  $log->info("Validando datos de registro de usuario: Nombre: "
          . "$nombre, Apellido: $apellido, Usuario: $usuario, "
          . "Email: $email, Email2: $email2");
  //$log->info("Lararala");
  //Now Working!

It looks like the 2nd logging event is causing something, related to file system that causes an Internal Server Error.