I did noting ,when try to clear cache I see this error 
**Catchable fatal error: Object of class stdClass could not be converted to string includes/theme.inc on line 2742**


    foreach (array_keys($regions) as $region) {
        // Assign region to a region variable.
        $region_content = drupal_get_region_content($region);
    //	$tmp = (array) $variables[$region];
    	//ym(empty($tmp));
    //	if(empty($tmp))
        isset($variables[$region]) ? $variables[$region] .= $region_content : $variables[$region] = $region_content;



I google this error but didn't find anything, anybody know what is the  reason of this error and how can I resolve it?