Index: core/kernel/db/cat_dbitem.php
===================================================================
--- core/kernel/db/cat_dbitem.php	(revision 14393)
+++ core/kernel/db/cat_dbitem.php	(working copy)
@@ -59,10 +59,10 @@
 	function Create($force_id = false, $system_create = false)
 	{
 		// TODO: move to OnBeforeItemCreate method
-		if ($this->useFilenames) {
+		/*if ($this->useFilenames) {
 			$this->checkFilename();
 			$this->generateFilename();
-		}
+		}*/
 
 		$ret = parent::Create($force_id, $system_create);
 
@@ -104,7 +104,7 @@
 		$ret = parent::Update($id, $system_update);
 
 		if ($ret) {
-			$filename = $this->useFilenames ? $this->GetDBField('Filename') : '';
+			$filename = $this->useFilenames ? (string)$this->GetDBField('Filename') : '';
 			$sql = 'UPDATE '.$this->CategoryItemsTable().'
 					SET Filename = '.$this->Conn->qstr($filename).'
 					WHERE ItemResourceId = '.$this->GetDBField('ResourceId');
@@ -403,7 +403,7 @@
 				'ItemResourceId'	=>	$this->GetField('ResourceId'),
 				'PrimaryCat'		=>	$is_primary ? 1 : 0,
 				'ItemPrefix'		=>	$this->Prefix,
-				'Filename'			=>	$this->useFilenames ? $this->GetDBField('Filename') : '', // because some prefixes does not use filenames,
+				'Filename'			=>	$this->useFilenames ? (string)$this->GetDBField('Filename') : '', // because some prefixes does not use filenames,
 			);
 			$this->Conn->doInsert($fields_hash, $table);
 		}
Index: core/units/categories/categories_item.php
===================================================================
--- core/units/categories/categories_item.php	(revision 14393)
+++ core/units/categories/categories_item.php	(working copy)
@@ -18,6 +18,9 @@
 	{
 		function Create($force_id = false, $system_create = false)
 		{
+			$parent_category = $this->GetDBField('ParentId') > 0 ? $this->GetDBField('ParentId') : $this->Application->GetVar('m_cat_id');
+			$this->SetDBField('ParentId', $parent_category);
+
 			$this->checkFilename();
 			$this->generateFilename();
 
@@ -33,9 +36,6 @@
 				$this->SetDBField('CreatedById', $this->Application->RecallVar('user_id'));
 			}
 
-			$parent_category = $this->GetDBField('ParentId') > 0 ? $this->GetDBField('ParentId') : $this->Application->GetVar('m_cat_id');
-			$this->SetDBField('ParentId', $parent_category);
-
 			$ret = parent::Create($force_id, $system_create);
 
 			if ($ret) {
@@ -132,7 +132,7 @@
 			}
 
 			$unique_clause = '(Filename = %s) AND (ThemeId = ' . $item_theme . ' OR ThemeId = 0)';
-			$check_in_parent_cat_only = $item_id ? ' AND ParentId = ' . $this->GetDBField('ParentId') : '';
+			$check_in_parent_cat_only = ' AND ParentId = ' . $this->GetDBField('ParentId');
 
 			// check temp table
 			$sql_temp = '	SELECT ' . $this->IDField . '
Index: core/units/helpers/filenames_helper.php
===================================================================
--- core/units/helpers/filenames_helper.php	(revision 14393)
+++ core/units/helpers/filenames_helper.php	(working copy)
@@ -95,7 +95,7 @@
 
 		$item_id = !$item_id ? 0 : $item_id;
 
-		if ($table == TABLE_PREFIX.'CategoryItems') {
+		if ( $this->Application->GetLiveName($table) == TABLE_PREFIX.'CategoryItems' ) {
 			$item_categories_cur = $this->Conn->GetCol('SELECT CategoryId FROM '.$table.' WHERE ItemResourceId = '.$item_id);
 			$item_categories_live = $this->Application->IsTempTable($table) ? $this->Conn->GetCol('SELECT CategoryId FROM '.$this->Application->GetLiveName($table).' WHERE ItemResourceId = '.$item_id) : array();