Try Clear cookies and site data from the padlock icon in the address bar and do a hard refresh by holding down the Shift key while clicking the refresh button.

This doesn't solve my problem.

You can remove all data stored in Firefox for a specific domain via "Forget About This Site" in the right-click context menu of an history entry ("History -> Show All History" or "View -> Sidebar -> History").

Using "Forget About This Site" will remove all data stored in Firefox for this domain like history and cookies and passwords and exceptions and cache, so be cautious. If you have a password or other data for that domain that you do not want to lose, make sure to backup this data or make a note.

You can't recover from this 'forget' unless you have a backup of involved files.

If you revisit a 'forgotten' website, data for that website will be saved once again.

• https://support.mozilla.org/en-US/kb/delete-browsing-search-download-history-firefox

Not working! Beliave me I have uninstalled the Firefox and deleted all the traces from computer (Regedit to). With other browser works. No Firefox.

Does it still happen in Troubleshoot Mode?

Yes! I have tried everything I found on Internet. Nothing works.

Does it still happen in a new profile? An easy way to test a new profile is to install Developer Edition and see if it happens there or refresh your existing profile.

The resource at “https://adservice.google.ro/adsid/google/ui?gadsid=AORoGNTIM8v0-orb8s-gYQ1fXCHtb77eht-Ab7Z3LRwcaSNCSYzX3O-84A” was blocked by OpaqueResponseBlocking. Reason: “nosniff is true and mimeType is an opaque-blocklisted MIME type or its essence is 'text/plain'”.

This is the message that I receive in Browser Console.

Try to set this browser.opaqueResponseBlocking pref to false on the about:config page.

• browser.opaqueResponseBlocking.javascriptValidator = false

You can open the about:config page via the location/address bar. On the warning page, you can click "Accept the Risk and Continue" to open about:config.

• https://support.mozilla.org/en-US/kb/about-config-editor-firefox

Not working. I setup the about: config like was.

Did you try Developer Edition?