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The following pop-up is preventing me from using Firefox, how do I fix it? Pop-up: "TypeError: Components.classes['@threatexpert.com/XPCOM/BDCoreAccess;1'] is undefined"

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  • Last reply by Rob

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Firefox was crashing for a while, reinstalling seemed to help after a few tries, but updating to the new version left some of my add ons uncompatible. It was right after I updated my spyware detector that this pop-up started occuring. Most of the time it immediately reapears when I close it and won't let me use firefox, I have to use task manager to close it.

Firefox was crashing for a while, reinstalling seemed to help after a few tries, but updating to the new version left some of my add ons uncompatible. It was right after I updated my spyware detector that this pop-up started occuring. Most of the time it immediately reapears when I close it and won't let me use firefox, I have to use task manager to close it.

Chosen solution

Do you have software from PC Tools installed?


This issue is caused by an extension that isn't working properly.

Start Firefox in Use Troubleshoot Mode in Firefox to check if one of the extensions or if hardware acceleration is causing the problem (switch to the DEFAULT theme: Firefox (Tools) > Add-ons > Appearance/Themes).

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Chosen Solution

Do you have software from PC Tools installed?


This issue is caused by an extension that isn't working properly.

Start Firefox in Use Troubleshoot Mode in Firefox to check if one of the extensions or if hardware acceleration is causing the problem (switch to the DEFAULT theme: Firefox (Tools) > Add-ons > Appearance/Themes).

Modified by cor-el

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It worked, I was confused when looking at a similar problem's solution because I wasn't sure if Firefox had its own safe mode and didn't know what button to push to get to it.

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It works with no problems in 7.0.1 and all other browsers I've tried, so suggest the problem lies in 8.0.1 not PC Tools. Let me know when its fixed and I'll upgrade.

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I just tried 9.0.1 and the problem is still there. This is more than disappointing. I have reverted to 7.0.1 which still works with no problems. The problem is clearly with Firefox as all other browsers work with the PC Tools software. Time to abandon ship and try Chrome?

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Yep, that's the solution for add-on's that aren't compatible with the latest versions of Firefox - get rid of the browser altogether rather than eliminate the actual cause.

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Same problem with FF 10.0.2 and PCTools. Used Cor-el's recommendation which solved the problem. Specifically, re-started in safe mode with all extensions disabled, then enabled the compatibility checker, and restarted with extensions enabled. No more pop-ups.

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The actual Solution (for Nightly) is to go to the Menu [Tools][Add-ons][Extensions] and choose "Browser Guard Toolbar 4.0.0.1550" (with the "Add-On Compatibility Reporter 1.1" Extension Installed).

Click on the [Compatibility] Button and choose "This Add-on no longer works".

That will leave as many things installed and working as is possible (IE: no need to uninstall PCTools or your Browser) and the 'Add-On' will still work were it is able to (with older versions of FF and with IE (under WinXP)).

For a bonus it will report the incompatibility for you.


You'll need a big Stick to beat that.


YT, Rob