Files download from 'Images and Attachments' should not be renamed "DownloadImage"

I've put files related to the part in the Images and Attachments tab.  They include a DXF.  When I download the DXF file it looses its name and file type, the file is downloaded as "DownloadImage" with no file type.  

This is very annoying.  When I download the DXF "562-4096.DXF" the file downloaded should not be renamed "DownloadImage" with no file type.

Please make it so the name of a file saved in the 'images and attachments' tab is not changed when downloading the file.