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xull.dll error.. reisntalled, formated pc new clean install etc dont work

  • 5 replies
  • 74 have this problem
  • 96 views
  • Last reply by Morbus

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Every time i try, my firefox give me this error... "xull.dll missing" My antivirus is up to date, my pc dont have malware or virus, every other program, browser or game works perfect, i tried a fresh install after formating a new pc, even so i had no luck... This problem started with firefox 3.0.17 and every version after that, im using version 3.6 now, and i have to copy a new xull.dll every time i open this browser. Ireally like firefox, but this is too much sorry.

This happened

Every time Firefox opened

== This problem started with firefox 3.0.17 and every version after that, im using version 3.6 now

All Replies (5)

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Hello Anderson.

The version of Firefox you posted this on is 3.0, not 3.6. I hope you know that. Firefox 3.0 is no longer supported.

As for your problem, I don't understand what's happening. When exactly does the error appear?

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Hello, im using this old version because this way sometimes this error do not occur.

"What Is Xul.dll And Why Does It Cause Errors?

Xul.dll is a file that the FireFox web browser uses to control the Internet browsing speed and reliability of your PC. This file has been used a lot by FireFox through its various versions, and is a vital part of this program. However, it’s also one of the main causes of problems for the Firefox browser. Here are some of the errors which you will typically see caused by the xul.dll file:

   Firefox.exe – Bad Image
   C:\Program Files\mozilla Firefox\xul.dll is either not designed to run on WINDOWS or it contains an error. Try installing program again.

or

   XUL.DLL is not valid without reinstall

or

   This application has failed to start because xul.dll was not found. Re-installing the application may fix the problem"


These errors, sometimes one, sometimes another. I really think you know about these already...

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Remember, Firefox is community driven, and so is SUMO (support.mozilla.org). I don't know of these errors, I'm sorry, so I probably can't help you a lot. If Firefox, for some reason, can't detect xul.dll, maybe your firewall or some security application is denying access.

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A clean reinstall by deleting the Firefox program folder before reinstalling should fix issues with old or incompatible files.

If that doesn't work the also do a malware check with a few malware scan programs. You need to use all programs because each detects different malware.

http://www.malwarebytes.org/mbam.php - Malwarebytes' Anti-Malware http://www.superantispyware.com/ - SuperAntispyware http://www.safer-networking.org/en/index.html - Spybot Search & Destroy http://www.lavasoft.com/products/ad_aware_free.php - Ad-Aware Free http://www.microsoft.com/windows/products/winfamily/defender/default.mspx - Windows Defender: Home Page .......... See also "Spyware on Windows": http://kb.mozillazine.org/Popups_not_blocked

Also make sure that your anti-virus program isn't causing that issue.

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Thank you, but is not malware, im using Spybot Search and Destroy and avast 2010 fully updated, and i dont have any other problems or error with any other aplications or games, only with this browser and xull.dll.