Do you have a file action for docx? Tools > Options > Applications

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

You can try to delete the mimeTypes.rdf file in the Firefox profile folder to reset all file actions.

• http://kb.mozillazine.org/mimeTypes.rdf
• http://kb.mozillazine.org/File_types_and_download_actions#Resetting_download_actions

Firefox can open text letters sent to me as a pdf file, but will not open letters sent to me as a docx file. I click OK to open in firefox mode, and I get nothing, just a new tab shows in the upper bar??

I have a file action for docx? I clicked on Tools > Options > Applications 

and tried to open the docx file in notepad, it comes up in all unreadable letters, I tried opening in open office 2.4 and it says the document is corrupted, and when I click on firefox to open it, nothing happens, just an open tab at the top bar, but nothing opens or shows up on my screen?? So, how will firefox open this docx file for me, or do I have to download later open office or notepad software? Is there a way I can just convert the docx file to a pdf file, because I have no problems opening pdf files!! Can anybody help me solve this ?? Thanks, geoarn.

DOCX is a container (zip) archive, so you can try to add a .zip file extension to see if you can inspect its content with an archive manager.
If open office can't open this file then it may indeed be corrupted or the file may be in an unsupported format.

It is possible that anti-virus software is corrupting downloaded files or is otherwise interfering with downloading files.

Try to disable the real-time (live) scanning of files in your anti-virus software temporarily to see if that makes downloading work.

See:

• http://kb.mozillazine.org/Unable_to_save_or_download_files
• browser.download.manager.scanWhenDone

Hi geoarn, I assume you do not have Microsoft Office, since Firefox should be able to discover Microsoft Office settings in the registry. Or, if you have a version earlier than Office 2007, you may not have the converter pack.

How do you generally open word processing documents? Do you use Microsoft Office 2003 or earlier, or another suite, such as WordPerfect, OpenOffice, or LibreOffice?

Sorry, I see you have OpenOffice 2.4. That version date back to 2008 and may not have the best converter for DOCX files. Can you update to a more recent version? Depending your internet connection it could take a while (huge file): http://www.openoffice.org/download/