hello, this might be an issue with malicious software on your pc. please perform all these steps:

1. reset firefox (this will keep your bookmarks and passwords)
2. afterwards go to the firefox menu ≡ > addons > extensions and in case there are still extensions listed there, disable them.
3. run a full scan of your system with different security tools like the free version of malwarebytes and adwcleaner to make sure that adware isn't present in other places of your system as well.
4. finally update your plugins (some of them are out-dated & have security vulnerabilities that are actively exploited on the web).

Troubleshoot Firefox issues caused by malware

If you have submitted crash reports then please post the IDs of one or more recent crash reports that have a "bp-" prefix:

• bp-xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx

You can find the Report ID of recent crash reports on the "Help > Troubleshooting Information" page (about:support).

• Click the "All Crash Reports" button on this page to open the about:crashes page and see all crash reports.

If necessary then you can open about: pages via the location/address bar.

See:

• http://kb.mozillazine.org/Mozilla_Crash_Reporter
• https://support.mozilla.org/kb/Mozilla+Crash+Reporter

Please update the Flash plugin. The currently installed version is outdated and has known security vulnerabilities.

• https://www.mozilla.org/plugincheck/

You can find the latest Flash player versions for Firefox on this page:

• http://www.adobe.com/special/products/flashplayer/fp_distribution3.html