Index: branches/RC/core/units/categories/categories_tag_processor.php
===================================================================
diff -u -N -r11610 -r11648
--- branches/RC/core/units/categories/categories_tag_processor.php	(.../categories_tag_processor.php)	(revision 11610)
+++ branches/RC/core/units/categories/categories_tag_processor.php	(.../categories_tag_processor.php)	(revision 11648)
@@ -1198,6 +1198,11 @@
 		$templates = $this->Conn->GetCol($sql, 'CategoryId');
 
 		foreach ($page_ids as $page_id) {
+			if (!array_key_exists($page_id, $templates)) {
+				// internal page was deleted, but link to it was found in given content block data
+				continue;
+			}
+
 			$text = preg_replace('/@@' . $page_id . '@@/', $this->Application->HREF($templates[$page_id], '', Array ('pass' => 'm')), $text);
 		}