User register function producing errors

When a user tries to register, Omeka (version 1.5.3) shows numerous errors above the registration fields:

# Time Memory Function Location
1 0.0000 238608 {main}( ) ../index.php:0
2 0.0865 5035288 Omeka_Core->run( ) ../index.php:28
3 0.0865 5035344 Zend_Application->run( ) ../Core.php:165
4 0.0866 5035392 Zend_Application_Bootstrap_Bootstrap->run( ) ../Application.php:366
5 0.0866 5035768 Zend_Controller_Front->dispatch( ) ../Bootstrap.php:97
6 0.0910 5174040 Zend_Controller_Dispatcher_Standard->dispatch( ) ../Front.php:954
7 0.0912 5175408 Zend_Controller_Dispatcher_Standard->loadClass( ) ../Standard.php:262
8 0.0913 5180104 include_once( '/home/omeka/plugins/MyOmeka/controllers/MyOmekaController.php' ) ../Standard.php:344
9 0.0916 5236016 require_once( '/home/omeka/plugins/MyOmeka/models/MyOmekaPoster.php' ) ../MyOmekaController.php:8