Do you get an error message or just... nothing happens.

If there's no message, you can check the Windows Task Manager to see whether Firefox stalled during startup and if it has, terminate it so you can try again.

Ctrl+Shift+Esc will display the Task Manager. Click the Processes tab and look for firefox.exe. You can right-click it and End Process. Windows will warn you about possible data loss, so of course you would only do this when Firefox can't be started or shut down normally.

You might also try starting Firefox in its Safe Mode. That's a standard diagnostic tool to deactivate extensions and some advanced features of Firefox. More info: Diagnose Firefox issues using Troubleshoot Mode.

When Firefox is not running, you can start Firefox in Safe Mode by holding down the Shift key when double-clicking the Firefox shortcut.

A small dialog should appear. Click "Start in Safe Mode" (not Reset).

Does it run?

Oh, and check out these articles:

• Firefox won't start - find solutions
• Fix problems connecting to websites after updating Firefox

Got the email but cannot even start Firefox in Safe Mode. The Task Manager is does not show CPU for firefox.exe *32. Tried to do a restore from an earlier version and I still cannot launch Firefox.

Tried the safe mode but it won't launch either. Am about 1/2 way thru a Norton scan and only 2 cookies show up.

It is possible that your security software (firewall, anti-virus) blocks or restricts Firefox or the plugin-container process without informing you, possibly after detecting changes (update) to the Firefox program.

Remove all rules for Firefox and the plugin-container from the permissions list in the firewall and let your firewall ask again for permission to get full unrestricted access to internet for Firefox and the plugin-container process and the updater process.

See:

• https://support.mozilla.org/kb/Server+not+found
• https://support.mozilla.org/kb/Firewalls

Boot the computer in Windows Safe mode with network support (press F8 on the boot screen) as a test to see if that helps.

• http://www.bleepingcomputer.com/tutorials/how-to-start-windows-in-safe-mode/

Create a new profile as a test to check if your current profile is causing the problem.

See "Creating a profile":

• https://support.mozilla.org/kb/profile-manager-create-and-remove-firefox-profiles
• http://kb.mozillazine.org/Standard_diagnostic_-_Firefox#Profile_issues

If the new profile works then you can transfer files from a previously used profile to the new profile, but be cautious not to copy corrupted files to avoid carrying over problems.

• http://kb.mozillazine.org/Transferring_data_to_a_new_profile_-_Firefox

Hi JerryHElkGrove, you mentioned "The Task Manager is does not show CPU for firefox.exe *32." I'm not sure whether you tried to terminate it or not?

For future reference, in the Task Manager, Processes Tab, if you click the View menu > Select Columns you can add columns like Memory and Read Bytes, which typically have more activity than CPU. Then you can confirm that firefox.exe is really frozen and ready to be terminated.

By creating a new directory I was able to install Firefox and not lose my bookmarks.