Firefox won't open

[billjohn]

Firefox icon highlights for a few seconds but does not open. I uninstall FF and re-install. It opens for a few times but then won't open.

I have used FF on my last three PCs. It started doing this three weeks ago. Only thing I can connect with that date (about) is the Java incident. Java is disabled. PC Tools Reg Repair runs every night and finds 20+ problems.

FF 20.0--Win 7, Athlon duel core, 4 Gb RAM, Tera HD, McAfee Sec. Center current and active.

[DanRaisch]

Does the same thing occur if you launch the application in Mozilla Safe Mode? http://kb.mozillazine.org/Safe_mode

[billjohn]

Thanks for the suggestion.

I evoked Safe mode. It said "Restart in Safe Mode" or similar. It did not re-start. Clicking on icon, did not re-start.

[DanRaisch]

Close all applications and reboot the computer.
Delete any downloaded or partially downloaded installer files.
Clear the browser cache (of whatever browser you are using to download FF) and the Windows Temp directory.
Shutdown any anti-virus software you are running.
Download a new copy of the full installer from www.mozilla.com
Delete the directory C:\Program Files\Mozilla Firefox
Run the installer.
Restart the anti-virus program.

[billjohn]

By the way, I have a problem with TBird on this computer also. It opens and operates fine for a few minutes to an hour. Then the Minimize, Maximize and Close functions will not work. The top most part of the screen is transparent. You cannot close the Ap.

I use both of these Aps on an old Laptop (Win XP) and a new Toshiba (Win 8) laptop and they work fine

[LIMPET235]

This may be the cause it if updated recently...
"McAfee Sec. Center current and active."

If the above, ^, doesn't work, the try removing all refs to Firefox in McAfee with Firefox closed,
then, re-start Firefox.

[billjohn]

Re deleting files:

Are there any user files that will be deleted (C:\Program Files\Mozilla Firefox) ?

[LIMPET235]

No.
They are the program files not your profile files.

[billjohn]

Tnx,

Got to go now, will try that tonight

[gh421]

Hi all
I have read so many 'fixes' that require loosing your profile to fix firefox not starting but an easier way is;
first terminate the firefox.exe process if it's running *open task manager and check running processes, if you see firefox.exe, stop it - need to do this or your changes might mentioned below might not take effect.
then
go to your profile director (mozilla) - ie, users/username/appdata/roaming/mozilla/firefox/profiles
open your profile directory, find prefs.js, rename it to "backup prefs.js"
restart firefox and you are back in business with all your bookmarks and saved passwords etc still intact.

[LIMPET235]

Mmmm,
Pity that you picked a thread from 2013 to reply to.

Locking due to old age.