HERE'S THE SOLUTION:
Please open CuteSoft_Client\CuteEditor\Dialogs\InsertImage.aspx and change the following code:
<CE:Uploader id="InputFile" runat="server"></CE:Uploader>
to:
<CE:Uploader id="InputFile" UploadType="IFrame" runat="server"></CE:Uploader>
It should resolve the problems.
do the same for all following files:
- InsertDocument.aspx
- InsertFlash.aspx
- InsertGallery.aspx
- InsertImage.aspx
- InsertMedia.aspx
- InsertTemplate.aspx
- SelectFile.aspx
- SelectImage.aspx