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Firefox won't start and the process id keeps changing

  • 4 replies
  • 1 has this problem
  • Last reply by M W Sasser

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Occasionally when I click Firefox, it won't start properly. If I check the windows task manager, there is a lone Firefox process but it's ID keeps changing.

If I click the icon a few more times, Firefox will spawn hundreds of instances and crash Explorer. At this point I can right-click and close all windows. Then Firefox can be started properly.

Any clue what's going on or how I can fix it?

All Replies (4)

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Outdated versions of Comodo Firewall or Comodo Antivirus security software (or a leftover file after Comodo was uninstalled) can cause Firefox not to start with no error message. Update Comodo to the latest version, if you have it installed. If Comodo software is not installed, check if there's a file called IseGuard64.dll or IseGuard32.dll in your C:\Windows\system32\ folder or your system drive and, if so, manually delete the file.

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I've never had that firewall installed on any of my workstations.

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Can you start Firefox in its safe mode? menu → help → restart with add-ons disabled

Can you start it in Windows Safe Mode?

If you can start it:

With Hardware Acceleration disabled in Preferences, under the Performance section?

With a new clean profile? about:profiles → create a new profile and set as default

You may be able to start profile manager without starting the browser. You can edit your shortcut to add --profilemanager after the path to the executable in the the Target field in the shortcut's properties. (Or you may have shortcuts in a Firefox folder in the Start Menu which will do these things.)

If nothing here helps, you may want to scan for malware using whatever security or antivirus software you already have. One to try if you do not have it is MalwareBytes Antimalware.

You might also look in the Event Viewer, in the Applications tab, to see what is logged when these issues take place. You can type eventvwr.msc in the Start Menu search or run box to open this.

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@crankygoat I am doing a forehead slap! Can't believe I forgot to check the Event Viewer Application logs.

When I have some hard data, I'll post it here.