I think what Firefox is telling you is it received a file, but does not know what to do with it. Are you downloading the file, or trying to open it with FF?

See also:

• https://support.mozilla.org/kb/change-firefox-behavior-when-open-file
• http://kb.mozillazine.org/File_types_and_download_actions

I'm using FF to select a file from a web enabled DB.......I only get this error on Word files. Excel or PPT opens fine.

 FYI - this started to happen about the time I installed MS Office 2013.   
Thanks - any suggestions would be most appreciated.

Thanks. Already read this stuff - no help. The Applications tab displays an empty box - nothing to select or change. Again - this only happens with MSWord files.........excel and ppt open OK

Next time, download the file as a file. Once the file is done, right click on it, select Properties > General. Under Opens With, make sure the correct program is set up for that type of file.

Hi Fred - I don't even get a chance to select 'file' - I do a single click, and it normally opens from there. But let me check a bit further with our DB folks....maybe they're changed something

right click on it using a file browser.

tried that already - I think - right click doesn't open the file in Word. It only seems to enable the image, or the icon representing the file. Sorry to be such trouble......this function in FF worked for years......the only thing that's new is MS Office 2013. Our DB administrator said nothing's different on the DB side of things. Do you think something within Windows7 has corrupted this? What would be the explanation of no entries in that Applications window within the Tools....Options...section?

I am getting confused. Let me start over;

Start Windows File Explorer. Look for one of the files that is giving you problems. Right click on the file. A menu should come up. On the bottom, select Properties. Under the General tab, look for Opens With. What program does it show?

thanks - all of the Word documents that I've placed on the DB show, in this "open with" window, "Word (desktop)"

should it list something else?

Is it the current word program you just installed?

Using the file explorer, what happens when you select a file and open it?

just above the "word (desktop)" it shows the old 2003 MSWord vers. But using Window's file Explorer, it opens MSWord 2013 when I double-click to open the file - it opens just fine.

Hmmm . . . . wait a minute, are you trying to open a file on your hard drive, or on another computer using Firefox?

first, you just asked me to use MS file Explorer to see what the properties were.,..and to ask what happened. Yes - that's on my hard drive. The problem I have is opening word files in a DB that is web enabled.....I've used Firefox browser for that, and everything else , for years...... When I look at the Tools, and options on FireFox., as your support page noted.....NOTHING is listed in the Applications tab....hence my note asking for help. The file I need to open is a Word file out on a web enabled DB. It's not on my hard drive - I have to problems opening docs there - but for that, I don't use Firefox