Index: moodle/lib/tablelib.php
--- moodle/lib/tablelib.php Base (1.24.2.5)
+++ moodle/lib/tablelib.php Locally Modified (Based On 1.24.2.5)
@@ -658,9 +658,22 @@
                         $fsortorder = get_string('asc');
                         $lsortorder = get_string('asc');
                     }
+
+                    $override = new object();
+                    $override->firstname = 'firstname';
+                    $override->lastname = 'lastname';
+                    $fullnamelanguage = get_string('fullnamedisplay', '', $override);
+                    
+                    if (($CFG->fullnamedisplay == 'firstname lastname') or
+                        ($CFG->fullnamedisplay == 'firstname') or
+                        ($CFG->fullnamedisplay == 'language' and $fullnamelanguage == 'firstname lastname' )) {
                     $this->headers[$index] = '<a href="'.$this->baseurl.$this->request[TABLE_VAR_SORT].'=firstname">'.get_string('firstname').get_accesshide(get_string('sortby').' '.get_string('firstname').' '.$fsortorder).'</a> '.$icon_sort_first.' / '.
                                              '<a href="'.$this->baseurl.$this->request[TABLE_VAR_SORT].'=lastname">'.get_string('lastname').get_accesshide(get_string('sortby').' '.get_string('lastname').' '.$lsortorder).'</a> '.$icon_sort_last;
+                    } else { 
+                        $this->headers[$index] = '<a href="'.$this->baseurl.$this->request[TABLE_VAR_SORT].'=lastname">'.get_string('lastname').get_accesshide(get_string('sortby').' '.get_string('lastname').' '.$lsortorder).'</a> '.$icon_sort_last.' / '.
+                                                 '<a href="'.$this->baseurl.$this->request[TABLE_VAR_SORT].'=firstname">'.get_string('firstname').get_accesshide(get_string('sortby').' '.get_string('firstname').' '.$fsortorder).'</a> '.$icon_sort_first;
                 }
+                }
                 break;
 
                 case 'userpic':