Unusual problem on image upload

Hi there, ichecked already the post on this subject but seems i-m having a strange behaviour on the upload:
On version 2.5.1 when i run the test.html i can see the files in the custom folder i choose, i can upload files and create folders (gives <Error number="0" originalDescription=""/> in this last case, but actually create the folders).
When i run the uploadtest.html i got the error 'error creating folder "D:\Inetpub\webs\mysite\public\" (File exists).
Also, if i try to browse the images on the server from the editor, the pop-up window becomes white as soon as i click on the browse server...
i've try both with relative path alone or completing the absolute too.
please help me!!!

$Config['Enabled'] = true ;

$Config['UserFilesPath'] = '/public/' ;

$Config['UserFilesAbsolutePath'] = 'D:\\Inetpub\\webs\\mysite\\public\\' ;