Index: modules/system/system.admin.inc
===================================================================
RCS file: /cvs/drupal/drupal/modules/system/system.admin.inc,v
retrieving revision 1.192
diff -u -p -r1.192 system.admin.inc
--- modules/system/system.admin.inc	24 Aug 2009 12:32:10 -0000	1.192
+++ modules/system/system.admin.inc	24 Aug 2009 20:22:54 -0000
@@ -1453,6 +1453,8 @@ function system_performance_settings() {
     '#default_value' => intval(variable_get('preprocess_js', 0) && $is_writable),
     '#disabled' => $disabled,
   );
+  
+  $form['#validate'][] = 'system_performance_settings_validate';
 
   $form['#submit'][] = 'drupal_clear_css_cache';
   $form['#submit'][] = 'drupal_clear_js_cache';
@@ -1461,6 +1463,15 @@ function system_performance_settings() {
 }
 
 /**
+ * Validation callback; remove button value before sending to system_settings_form_submit.
+ *
+ * @ingroup forms
+ */
+function system_performance_settings_validate($form, &$form_state) {
+  unset($form_state['values']['clear']);
+}
+
+/**
  * Submit callback; clear system caches.
  *
  * @ingroup forms