uploading does not work properly

I add several new resource types to the file manager’s browser window. I also changed browser/default/php/config and upload/default/php/config to add appropriate resource types’ info.

My config.php:

<?php
/*
*... ...
*/

global $Config ;

// SECURITY: You must explicitelly enable this "connector". (Set it to "true").
$Config['Enabled'] = true ;

// Path to user files relative to the document root.
$Config['UserFilesPath'] = '/UserFiles/' ;

$Config['UserFilesAbsolutePath'] = 'I:\\websites\\dev\UserFiles' ;

$Config['AllowedExtensions']['PDF']    = array('pdf') ;
$Config['DeniedExtensions']['PDF']    = array() ;

$Config['AllowedExtensions']['Image']    = array('jpg','gif','jpeg','png') ;
$Config['DeniedExtensions']['Image']    = array() ;

$Config['AllowedExtensions']['Media']    = array('swf','fla','jpg','gif','jpeg','png','avi','mpg','mpeg') ;
$Config['DeniedExtensions']['Media']    = array() ;

$Config['AllowedExtensions']['MS-Office']    = array('doc','ppt','xls','pdf') ;
$Config['DeniedExtensions']['MS-Office']    = array();

$Config['AllowedExtensions']['CAD']    = array('dwg') ;
$Config['DeniedExtensions']['CAD']    = array();

?>

A piece of my modified frmresourcetype.html:

var aTypes = [
['PDF','PDF'],
['Image','Image'],
['Media','Media'],
['MS-Office','MS-Office'],
['CAD','CAD']

I have created a CAD folder under /UserFiles/

My site is hosted in a Win2003 server machine. The admin told me he has given me full write access (for web users) to /userfiles and its sub folders.

The problem is that: Although the newly added types do appear in the drop-down list, I cannot upload anything to this resource type/to the folder. It shows that “Uploading in progress. Please wait...” and never responses.

I am totally lost. Any help?