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After downloading Firefox 64bit x64 Windows 7 Firefox 64bit x64 20.0a1 it will not open in window 7, any suggestion?


My OS Window 7 Professional 64 Bit

Firefox 14.0.1

Additional System Details

Installed Plug-ins

  • The QuickTime Plugin allows you to view a wide variety of multimedia content in Web pages. For more information, visit the QuickTime Web site.
  • Shockwave Flash 11.5 r502
  • Adobe Shockwave for Director Netscape plug-in, version
  • Next Generation Java Plug-in 10.9.2 for Mozilla browsers
  • Google Update
  • NPRuntime Script Plug-in Library for Java(TM) Deploy
  • iTunes Detector Plug-in
  • Adobe PDF Plug-In For Firefox and Netscape 10.1.4
  • Adobe Shockwave for Director Netscape plug-in, version
  • 5.1.10411.0
  • Unity Player 3.4.2f3
  • The plug-in allows you to open and edit files using Microsoft Office applications
  • Office Authorization plug-in for NPAPI browsers


  • User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:14.0) Gecko/20100101 Firefox/14.0.1

More Information

The message after trying to install it is; Windows needs to know what to use to open this program.

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251 solutions 3015 answers

The latest version of Firefox is 17.0.1

Try the Firefox Safe Mode to see how it works there. The Safe Mode is a troubleshooting mode, which disables most add-ons.

(If you're not using it, switch to the Default theme.)

  • You can open the Firefox 4.0+ Safe Mode by holding the Shift key when you use the Firefox desktop or Start menu shortcut.
  • Or use the Help menu item and click on the Restart with Add-ons Disabled... menu item while Firefox is running.

Don't select anything right now, just use "'Start in Safe Mode" To exit the Firefox Safe Mode, just close Firefox and wait a few seconds before using the Firefox shortcut (without the Shift key) to open it again. If it is good in the Firefox Safe Mode, your problem is probably caused by an extension, and you need to figure out which one.

Please follow the Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems article for that.

When you figure out what's causing your issues, please let us know. It might help other users who have the same problem.

meerkatweb 0 solutions 1 answers

I had the same problem. Installed/unistalled many times, but I've just fixed it this way:

1, Uninstall Firefox (if you haven't already)

2. In windows search box type:


(and run search)

If it finds a match in your AppData folder such as: \yourprofilename\AppData\Roaming\Mozilla\Firefox

Then delete the Mozilla folder and reinstall Firefox. It worked fine for me after that, hope it works for you.

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437 solutions 3144 answers

Helpful Reply

No you did not have the same problem and deleting that firefox Profile folder as suggested is not a good idea unless you do not care about your Bookmarks, passwords and and other such settings. Start Firefox with Profilemanager if you need to create a new client Profile.