Can you download and launch Word files normally from other sites, such as: http://download.microsoft.com/downloa.../internetexplorer8.doc

If so, it could be an issue on the mail provider's server. If the mail server is sending a generic content type ("application/octet-stream"), then Firefox won't actually associate that with any particular application (I suspect because it also is used for executable files).

Sometimes the Open/Save/Cancel dialog will show you the "content type" indicated by the server. Is that information available?

Is this a mail provider that would accept some constructive input on this issue?

I have two accounts, one BT Yahoo mail and the other normal Yahoo mail, I have the same problem in both.

When the open/save box comes up it says "you have chosen to open [filename] which is a doc file".

I have done some further testing and bizarrely:

-the file you linked comes up in Word just fine

-the .doc attachments open automatically in Word from other computers using FF or on this one if I use Internet Explorer.

So the problem is only when I'm specifically using FF on this particular computer to open email attachments.

Are there any differences in your Firefox add-ons (esp. any download-related extensions) or external security/proxy software between the two PCs (i.e., the one where Firefox works normally and the one where it doesn't)?

Actually, you might as well try resetting your application options first before doing all that comparing in case it's just a glitch. This involves renaming a file in your personal settings (AKA Firefox profile) folder. The steps are in this article: https://support.mozilla.org/en-US/kb/cant-download-or-save-files#w_reset-...

Okay I've tried that and it doesn't solve the problem - I didn't think it would since I'd already reinstalled FF from scratch with default settings.

I think the problem must lie with MS Office, since I've noticed a couple of other problems while trying to fix this - some of the file icons are strange and no MS Office programs appear on the "Set Default Programs" list. (Weirdly though, FF will happily open Excel attachments)

Thanks anyway for your help! I will try to find out what the problem is with Office and that might fix it.