It could be an add-on. Try disabling ALL nonessential and/or unrecognized extensions on the following page, restart Firefox, and see whether that makes any difference:

orange Firefox button or classic Tools menu > Add-ons > Extensions category

ya it works thank you very much

There are other things that need your attention.

Please Update to the latest Firefox 17.0.x version.

• Help > About Firefox

• https://support.mozilla.org/kb/update-firefox-latest-version

The Firefox Firefox 15.0.1 version that you currently run is no longer supported with security updates.

• http://www.mozilla.org/security/known-vulnerabilities/firefox.html

Diese Meldung erscheint im opera der ja bekanntlich nicht die molilla-addons verwendet, es wurde auch nichts an seiten zum Verfälschen der Browserausgabe gewählt, also kann es nicht nr an irgendwelchen Addons liegen, dass diese Meldung erdscheint

Hi Tina2012, did you try Firefox's Safe Mode? Diagnose Firefox issues using Troubleshoot Mode

Such issues can have different causes.
Sometimes the presence of third-party cookies from that site may be sufficient.

• https://support.mozilla.org/kb/Disabling+third+party+cookies

It is also possible to opt-out from such advertising companies.

• http://www.aboutads.info/choices/