[Thaliada]

That is indeed the problem, actually

if(!isset($_GET['folderid']) || trim($_GET['folderid']) == '') $_GET['folderid'] = 0;

should take care of this problem, but as i see now, i forgott to change

AND pm.folderid=" . mysql_real_escape_string($_GET['folderid']) . " ";

it in the query later on...

Sry just change

AND pm.folderid=" . mysql_real_escape_string($_GET['folderid']) . " ";

with

AND pm.folderid=" . mysql_real_escape_string($search_folderid) . " ";

That should fix this problem.