Hi, open the 3-bar menu > Add-ons > Extensions, then look for and remove/disable anything you don't recognise. Restart Firefox afterwards. ---------------- Hold down the Shift key when you start Firefox to start in Safe Mode. More - [[Troubleshoot Firefox issues using Safe Mode]]. If it's OK in Safe Mode, disable any theme or extensions you have - 3-bar menu > Add-ons > Themes/Extensions, then restart Firefox; now if it's still OK, re-enable them one by one until you find the culprit. You may need to restart Firefox after enabling some extensions. --------------------- Another thing you can do is to look in your PC for any recently installed programs that you don't recognise. You can try these free programs to scan for malware, which work with your existing antivirus software: * [https://www.microsoft.com/en-us/wdsi/products/scanner Microsoft Safety Scanner] * [http://www.malwarebytes.org/products/malwarebytes_free/ MalwareBytes' Anti-Malware] * [http://support.kaspersky.com/viruses/disinfection/5350 Anti-Rootkit Utility - TDSSKiller] (for more info, see this [https://www.bleepingcomputer.com/download/tdsskiller/ alternate TDSSKiller download page]) * [https://www.malwarebytes.com/adwcleaner/ AdwCleaner] (for more info, see this [http://www.bleepingcomputer.com/download/adwcleaner/ alternate AdwCleaner download page]) * [http://www.surfright.nl/en/hitmanpro/ Hitman Pro] * [http://www.eset.com/us/online-scanner/ ESET Online Scanner] '''Note that not all removal programs will detect all malware, so you may need to run several of them.''' Further information can be found in the [[Troubleshoot Firefox issues caused by malware]] article. ''If your question is resolved by this or another answer, please help other users by marking the best reply as Solved. Thank you!''