We are having the same problem here. We are running Windows 2003 server, sitefinity 3.5, we have added all 4 isapi mappings.
All uploads are looking like they are going into the DB,
into the following tables sf_CmsBinaryContent and sf_CmsContentThumbnail
but when displaying them the URL is incorrect and does not get images or documents out.
It is currently going to http://localhost/OURwebsite/Libraries/Image_Library/SideOrders.sflb.ashx
We have exhausted all avenues and research on this.
Can you provide any assistrance?