First start firefox in safe mode, sometimes the problem is caused by an addon: *[https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-using-safe-mode Firefox in safe mode] Try also scan your PC: *[https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-caused-malware Problems caused by malwares] Check the list of your installed programs in Control Painel: *http://www.wikihow.com/Remove-Programs-%28Windows-7%29

*http://malwarefixes.com/remove-snap-do-from-internet-browser/ *http://deletemalware.blogspot.com/2013/01/remove-snap-do.html *AdwCleaner:<br>http://www.bleepingcomputer.com/download/adwcleaner/<br>http://www.softpedia.com/get/Antivirus/Removal-Tools/AdwCleaner.shtml

Thanks!