- Click on the "Tools" menu and then select "Add-ons".
- Click on the "Extensions" button on the left side of the page that comes up.
- Click the "Disable" button beside each item on this list.
- Click on the "Plugins" menu on the left side of the page. Click the drop-down menu on the right and select "Never Activate" beside any item whose name does not start with "Adobe", "Flash", 'Microsoft', "Shockwave", "Windows" or "Java".
Once you have completed this, please restart your browser. If the error does not occur, it was caused by a plugin or extension.
You may determine which plugin is causing the error by re-enabling them one by one in the Add-ons Manager. When the problem occurs again, you will have found the offending plugin.