Index: install/upgrades.php
===================================================================
--- install/upgrades.php	(revision 14719)
+++ install/upgrades.php	(working copy)
@@ -614,7 +614,7 @@
 		function _moveDatabaseFolders()
 		{
 			// Tables: PageContent, Images
-			if ($this->Conn->TableFound('PageContent')) {
+			if ($this->Conn->TableFound('PageContent', true)) {
 				// 1. replaces "/kernel/user_files/" references in content blocks
 				$ml_helper =& $this->Application->recallObject('kMultiLanguageHelper');
 				/* @var $ml_helper kMultiLanguageHelper */
@@ -993,7 +993,7 @@
 			}
 
 			// 2. process "PageContent" table
-			if ($this->Conn->TableFound(TABLE_PREFIX . 'PageContent')) {
+			if ($this->Conn->TableFound(TABLE_PREFIX . 'PageContent', true)) {
 				$structure = $this->Conn->Query('DESCRIBE ' . TABLE_PREFIX . 'PageContent', 'Field');
 				if (!array_key_exists('l1_Translated', $structure)) {
 					$sql = "ALTER TABLE " . TABLE_PREFIX . "PageContent
@@ -1007,7 +1007,7 @@
 			}
 
 			// 3. process "FormFields" table
-			if ($this->Conn->TableFound(TABLE_PREFIX . 'FormFields')) {
+			if ($this->Conn->TableFound(TABLE_PREFIX . 'FormFields', true)) {
 				$structure = $this->Conn->Query('DESCRIBE ' . TABLE_PREFIX . 'FormFields', 'Field');
 				if (!$structure['FormId']['Key']) {
 					$sql = "ALTER TABLE " . TABLE_PREFIX . "FormFields
@@ -1027,7 +1027,7 @@
 			}
 
 			// 4. process "FormSubmissions" table
-			if ($this->Conn->TableFound(TABLE_PREFIX . 'FormSubmissions')) {
+			if ($this->Conn->TableFound(TABLE_PREFIX . 'FormSubmissions', true)) {
 				$structure = $this->Conn->Query('DESCRIBE ' . TABLE_PREFIX . 'FormSubmissions', 'Field');
 				if (!$structure['SubmissionTime']['Key']) {
 					$sql = "ALTER TABLE " . TABLE_PREFIX . "FormSubmissions
@@ -1444,7 +1444,7 @@
 				$ml_helper->createFields('emailevents');
 				$languages = $ml_helper->getLanguages();
 
-				if ($this->Conn->TableFound(TABLE_PREFIX . 'EmailMessage')) {
+				if ($this->Conn->TableFound(TABLE_PREFIX . 'EmailMessage', true)) {
 					$email_message_helper =& $this->Application->recallObject('EmailMessageHelper');
 					/* @var $email_message_helper EmailMessageHelper */
 
Index: kernel/application.php
===================================================================
--- kernel/application.php	(revision 14719)
+++ kernel/application.php	(working copy)
@@ -445,7 +445,7 @@
 	 */
 	public function refreshModuleInfo()
 	{
-		if (defined('IS_INSTALL') && IS_INSTALL && !$this->TableFound('Modules')) {
+		if (defined('IS_INSTALL') && IS_INSTALL && !$this->TableFound('Modules', true)) {
 			$this->registerModuleConstants();
 			return ;
 		}
@@ -2630,11 +2630,12 @@
 	 * Allows to detect table's presense in database
 	 *
 	 * @param string $table_name
+	 * @param bool $force
 	 * @return bool
 	 */
-	function TableFound($table_name)
+	function TableFound($table_name, $force = false)
 	{
-		return $this->Conn->TableFound($table_name);
+		return $this->Conn->TableFound($table_name, $force);
 	}
 
 	/**
Index: kernel/db/db_connection.php
===================================================================
--- kernel/db/db_connection.php	(revision 14719)
+++ kernel/db/db_connection.php	(working copy)
@@ -920,22 +920,30 @@
 		 * Allows to detect table's presence in database
 		 *
 		 * @param string $table_name
+		 * @param bool $force
 		 * @return bool
 		 * @access public
 		 */
-		public function TableFound($table_name)
+		public function TableFound($table_name, $force = false)
 		{
-			static $table_found = Array();
+			static $table_found = false;
 
+			if ($table_found === false) {
+				$table_found = array_flip($this->GetCol('SHOW TABLES'));
+			}
+
 			if (!preg_match('/^'.preg_quote(TABLE_PREFIX, '/').'(.*)/', $table_name)) {
 				$table_name = TABLE_PREFIX.$table_name;
 			}
 
-			if (!isset($table_found[$table_name])) {
-				$table_found[$table_name] = $this->Query('SHOW TABLES LIKE "'.$table_name.'"');
+			if ($force) {
+				if ($this->Query('SHOW TABLES LIKE '.$this->qstr($table_name))) {
+					$table_found[$table_name] = 1;
+				} else {
+					unset($table_found[$table_name]);
+				}
 			}
-
-			return $table_found[$table_name];
+			return isset($table_found[$table_name]);
 		}
 
 		/**
Index: kernel/managers/cache_manager.php
===================================================================
--- kernel/managers/cache_manager.php	(revision 14719)
+++ kernel/managers/cache_manager.php	(working copy)
@@ -173,7 +173,7 @@
 			return $this->configVariables[$name];
 		}
 
-		if ( defined('IS_INSTALL') && IS_INSTALL && !$this->Application->TableFound('ConfigurationValues') ) {
+		if ( defined('IS_INSTALL') && IS_INSTALL && !$this->Application->TableFound('ConfigurationValues', true) ) {
 			return false;
 		}
 
Index: kernel/session/session_storage.php
===================================================================
--- kernel/session/session_storage.php	(revision 14719)
+++ kernel/session/session_storage.php	(working copy)
@@ -120,7 +120,7 @@
 	 */
 	public function StoreSession($to_database = true)
 	{
-		if ( defined('IS_INSTALL') && IS_INSTALL && $to_database && !$this->Application->TableFound($this->TableName) ) {
+		if ( defined('IS_INSTALL') && IS_INSTALL && $to_database && !$this->Application->TableFound($this->TableName, true) ) {
 			return;
 		}
 
Index: units/custom_data/custom_data_event_handler.php
===================================================================
--- units/custom_data/custom_data_event_handler.php	(revision 14719)
+++ units/custom_data/custom_data_event_handler.php	(working copy)
@@ -40,7 +40,7 @@
 		 * Returns list of custom fields for a given $prefix
 		 *
 		 * @param $prefix
-		 * 
+		 *
 		 * @return Array|bool
 		 * @access protected
 		 */
@@ -48,7 +48,7 @@
 		{
 			static $custom_fields = Array ();
 
-			if (defined('IS_INSTALL') && IS_INSTALL && !$this->Application->TableFound('CustomField')) {
+			if (defined('IS_INSTALL') && IS_INSTALL && !$this->Application->TableFound('CustomField', true)) {
 				return false;
 			}
 
@@ -141,7 +141,7 @@
 				$fields['cust_' . $custom_id] = $field_options;
 				$fields['cust_' . $custom_id]['force_primary'] = !$custom_params['MultiLingual'];
 			}
-			
+
 			$this->Application->setUnitOption($event->Prefix, 'Fields', $fields);
 		}
 
Index: units/helpers/multilanguage_helper.php
===================================================================
--- units/helpers/multilanguage_helper.php	(revision 14719)
+++ units/helpers/multilanguage_helper.php	(working copy)
@@ -172,7 +172,9 @@
 			$table_name = $this->Application->getUnitOption($prefix, 'TableName');
 			$this->curFields = $this->Application->getUnitOption($prefix, 'Fields');
 
-			if ( !($table_name && $this->curFields) || ($table_name && !$this->Conn->TableFound($table_name)) ) {
+			$need_forced_table_check = kUtil::constOn('IS_INSTALL');
+
+			if ( !($table_name && $this->curFields) || ($table_name && !$this->Conn->TableFound($table_name, $need_forced_table_check)) ) {
 				// invalid config found or prefix not found
 				return ;
 			}
@@ -245,7 +247,9 @@
 			$table_name = $this->Application->getUnitOption($prefix, 'TableName');
 			$this->curFields = $this->Application->getUnitOption($prefix, 'Fields');
 
-			if ( !($table_name && $this->curFields) || ($table_name && !$this->Conn->TableFound($table_name)) ) {
+			$need_forced_table_check = kUtil::constOn('IS_INSTALL');
+
+			if ( !($table_name && $this->curFields) || ($table_name && !$this->Conn->TableFound($table_name, $need_forced_table_check)) ) {
 				// invalid config found or prefix not found
 				return ;
 			}