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How to fix: TypeError: Components.classes[cid_siterank] is undefined

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how do you fix "TypeError: Components.classes[cid_siterank] is undefined I have had nothing but problems with firefox. Every time I try to manuver around the above error message appears, and I can't go any further until I click on it.

how do you fix "TypeError: Components.classes[cid_siterank] is undefined'' I have had nothing but problems with firefox. Every time I try to manuver around the above error message appears, and I can't go any further until I click on it.

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