I have .SLDASM files on a mapped network drive, and also tried this thru IIS on local servers, and on a hosted server ... all don't work. When I click on a file:// url, nothing happens. I presume, it's because the .SLDASM is not associated with anything in my applications list. But .SLDPRT was already in the list ... which doesn't help me, but is worth noting. I've researched this, and it seems, to add an application to this list, I need to open the file, using FireFox, and when I get the open-dialog, check the "do this automatically" box. But, it's disabled. I could try to set-up a MIME type for it thru IIS. But, what I really need is for it to work with a mapped-drive (as it does with IE). Is there a spot in the registry I could add this to the list of Applications? I presume someone, at some point, added .SLDPRT ... what might it take to get that someone to add .SLDASM? Yes, I'm quite certain that someone was not me. == This happened == Every time Firefox opened == I first tried it