Solucionado error en version php del wamp

hola y saludos...
bueno amigos, estoy mamado llevo 1 dia sin poder estudiar ya que mi servidor php no funciona siendo que cuando ejecuto un proyecto ejemplo : login al validar usuario me sale un mensaje del browser que la conexion ha sido reiniciada.. no se pork??
viendo los logs de errores del wampserver 2.0 me salio esto
Código:
on line 31, referer: http://localhost/prueba/registrar.php
[Wed Nov 11 16:24:25 2009] [notice] Parent: child process exited with status 3221225477 -- Restarting.
[Wed Nov 11 16:24:26 2009] [notice] Apache/2.2.11 (Win32) PHP/5.3.0 configured -- resuming normal operations
[Wed Nov 11 16:24:26 2009] [notice] Server built: Dec 10 2008 00:10:06
[Wed Nov 11 16:24:26 2009] [notice] Parent: Created child process 3372
[Wed Nov 11 16:24:26 2009] [notice] Child 3372: Child process is running
[Wed Nov 11 16:24:26 2009] [notice] Child 3372: Acquired the start mutex.
[Wed Nov 11 16:24:26 2009] [notice] Child 3372: Starting 64 worker threads.
[Wed Nov 11 16:24:26 2009] [notice] Child 3372: Starting thread to listen on port 80.
[Wed Nov 11 16:27:40 2009] [notice] Parent: Received shutdown signal -- Shutting down the server.
[Wed Nov 11 16:27:40 2009] [notice] Child 3372: Exit event signaled. Child process is ending.
[Wed Nov 11 16:27:41 2009] [notice] Child 3372: Released the start mutex
[Wed Nov 11 16:27:42 2009] [notice] Child 3372: All worker threads have exited.
[Wed Nov 11 16:27:42 2009] [notice] Child 3372: Child process is exiting
[Wed Nov 11 16:27:43 2009] [notice] Parent: Child process exited successfully.
[Wed Nov 11 16:27:54 2009] [notice] Apache/2.2.11 (Win32) PHP/5.3.0 configured -- resuming normal operations
[Wed Nov 11 16:27:54 2009] [notice] Server built: Dec 10 2008 00:10:06
[Wed Nov 11 16:27:54 2009] [notice] Parent: Created child process 3172
[Wed Nov 11 16:27:55 2009] [notice] Child 3172: Child process is running
[Wed Nov 11 16:27:55 2009] [notice] Child 3172: Acquired the start mutex.
[Wed Nov 11 16:27:55 2009] [notice] Child 3172: Starting 64 worker threads.
[Wed Nov 11 16:27:55 2009] [notice] Child 3172: Starting thread to listen on port 80.
[Wed Nov 11 16:28:03 2009] [error] [client 127.0.0.1] PHP Notice:  Undefined variable: usuario in C:\\wamp\\www\\tallerphp\\validar_usuario.php on line 20, referer: http://localhost/tallerphp/login.php
[Wed Nov 11 16:28:09 2009] [notice] Parent: child process exited with status 3221225477 -- Restarting.
[Wed Nov 11 16:28:09 2009] [notice] Apache/2.2.11 (Win32) PHP/5.3.0 configured -- resuming normal operations
[Wed Nov 11 16:28:09 2009] [notice] Server built: Dec 10 2008 00:10:06
[Wed Nov 11 16:28:09 2009] [notice] Parent: Created child process 3564
[Wed Nov 11 16:28:09 2009] [notice] Child 3564: Child process is running
[Wed Nov 11 16:28:09 2009] [notice] Child 3564: Acquired the start mutex.
[Wed Nov 11 16:28:09 2009] [notice] Child 3564: Starting 64 worker threads.
[Wed Nov 11 16:28:09 2009] [notice] Child 3564: Starting thread to listen on port 80.
[Wed Nov 11 16:28:34 2009] [notice] Parent: Received shutdown signal -- Shutting down the server.
[Wed Nov 11 16:28:34 2009] [notice] Child 3564: Exit event signaled. Child process is ending.
[Wed Nov 11 16:28:35 2009] [notice] Child 3564: Released the start mutex
[Wed Nov 11 16:28:36 2009] [notice] Child 3564: All worker threads have exited.
[Wed Nov 11 16:28:36 2009] [notice] Child 3564: Child process is exiting
[Wed Nov 11 16:28:36 2009] [notice] Parent: Child process exited successfully.
[Wed Nov 11 16:28:37 2009] [notice] Apache/2.2.11 (Win32) PHP/5.3.0 configured -- resuming normal operations
[Wed Nov 11 16:28:37 2009] [notice] Server built: Dec 10 2008 00:10:06
[Wed Nov 11 16:28:37 2009] [notice] Parent: Created child process 2340
[Wed Nov 11 16:28:37 2009] [notice] Child 2340: Child process is running
[Wed Nov 11 16:28:37 2009] [notice] Child 2340: Acquired the start mutex.
[Wed Nov 11 16:28:37 2009] [notice] Child 2340: Starting 64 worker threads.
[Wed Nov 11 16:28:37 2009] [notice] Child 2340: Starting thread to listen on port 80.
[Wed Nov 11 16:30:03 2009] [error] [client 127.0.0.1] PHP Notice:  Undefined variable: usuario in C:\\wamp\\www\\tallerphp\\validar_usuario.php on line 20, referer: http://localhost/tallerphp/login.php
[Wed Nov 11 16:30:04 2009] [notice] Parent: child process exited with status 3221225477 -- Restarting.
[Wed Nov 11 16:30:04 2009] [notice] Apache/2.2.11 (Win32) PHP/5.3.0 configured -- resuming normal operations
[Wed Nov 11 16:30:04 2009] [notice] Server built: Dec 10 2008 00:10:06
[Wed Nov 11 16:30:04 2009] [notice] Parent: Created child process 1292
[Wed Nov 11 16:30:04 2009] [notice] Child 1292: Child process is running
[Wed Nov 11 16:30:04 2009] [notice] Child 1292: Acquired the start mutex.
[Wed Nov 11 16:30:04 2009] [notice] Child 1292: Starting 64 worker threads.
[Wed Nov 11 16:30:04 2009] [notice] Child 1292: Starting thread to listen on port 80.