find image/files with Internet Explorer

Hi,

with chrome and firefox no problem but with internet explorer (verion 8 and 9) when i click button to browse image/files in folder "userfile", the popup show me index.php (main page of site).

i use ckfinder+ckeditor in other sites without problems...but i cannot understand why on this server only with IE it doesn't work.

what i can i do to resolve it???

Thanks