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FF 18 will not start in Win7. Uninstalled and reinstalled several times.


Upgraded from v17. Since that time FF18 will not start at all. Clicked startup link and nothing happens.

Additional System Details


  • User Agent: Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; WOW64; Trident/5.0; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; Media Center PC 6.0; .NET4.0C; BRI/2; InfoPath.3; Creative AutoUpdate v1.41.07; BOIE9;ENUSMSE)

More Information

No information since FF18 will not start.

Tyler Downer
  • Administrator
  • Moderator
1164 solutions 6629 answers

It's possible you have malware preventing Firefox from opening. Troubleshoot Firefox issues caused by malware

  • Top 10 Contributor
  • Moderator
10738 solutions 96600 answers

A possible cause is security software (firewall,anti-virus) that 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.


Question owner

Thanks. I started FF18 in safe mode and it loaded. Turns out there was an incompatible extension that it could not resolve in normal windows mode. Works fine now.