What search engine opens?

See:

• https://support.mozilla.org/kb/remove-toolbar-has-taken-over-your-firefox-search-

Do a malware check with several malware scanning programs on the Windows computer.
Please scan with all programs because each program detects different malware.
All these programs have free versions.

Make sure that you update each program to get the latest version of their databases before doing a scan.

• Malwarebytes' Anti-Malware:
  http://www.malwarebytes.org/mbam.php
• AdwCleaner:
  http://www.bleepingcomputer.com/download/adwcleaner/
  http://www.softpedia.com/get/Antivirus/Removal-Tools/AdwCleaner.shtml
• SuperAntispyware:
  http://www.superantispyware.com/
• Microsoft Safety Scanner:
  http://www.microsoft.com/security/scanner/en-us/default.aspx
• Windows Defender:
  http://windows.microsoft.com/en-us/windows/using-defender
• Spybot Search & Destroy:
  http://www.safer-networking.org/en/index.html
• Kasperky Free Security Scan:
  http://www.kaspersky.com/security-scan

You can also do a check for a rootkit infection with TDSSKiller.

• Anti-rootkit utility TDSSKiller:
  http://support.kaspersky.com/5350?el=88446

See also:

• "Spyware on Windows": http://kb.mozillazine.org/Popups_not_blocked

Open a new window or tab. In the address bar, type about:config. If a warning screen comes up, press the Be Careful button. This is where Firefox finds information it needs to run. At the top of the screen is a search bar. Enter browser.newtab.url and press enter. browser.newtab.url tells Firefox what to show when a new tab is opened. If you want, right click and select Modify. You can change the setting to;

about:home (Firefox default home page),
about:newtab (shows the sites most visited),
about:blank (a blank page),
or you can enter any web page you want.

The same instructions are used for the new window setting, listed as browser.startup.homepage.

I have set the configuration to "about:newtab" and it tries to open the tab with the most viewed sites, but it is quickly over ridden with "torch" search site. I noticed in the config page that there is an entry:

browser.newtabpage.blocked;{"2hqFXXFK5XOSLkWgQYlqeg==":1,"2TiMBhGQSD1B9yYI/hSPew==":1,"h0WeSwFf7Y0MeiCXCrG+Tg==":1,"3nPfMHvnRyNKKojlQv+4SQ==":1,"0IYT5e36qa9ACx9r9LiGAA==":1,"arWFEk62VKVSOFJuofke9A==":1,"zZruOzT8OdkS05rWBzh+hw==":1,"ae74jiqv70iWPoFDa/i8hQ==":1,"RkZFA6jkhQwfs3zcAT9HWQ==":1,"KBjmWLAPZBvq76G3qnrpyA==":1,"6Oh+DlSCbPa+/gwh4WnhHg==":1,"7epRT8THBkR/35UZ4BF1EQ==":1,"biAx1qxX06aYGbq0h7tL3w==":1,"PWgT1Mb+5aavHvktCHxlHw==":1,"fDT2RnoqCd27w4WULFskPg==":1,"sB8dGH1ruXswyOnuu88x6A==":1,"Rmfq5BUuyVn3jSUME6gnug==":1,"VFnN9dFWDqfFz9zmI2vqwQ==":1,"BYJfe/4Gri1P4C7jQ+WPsw==":1,"AxFopbljIN0Gf3nEwHpLQg==":1,"Y/B4LP5l0gLAfHyLcpMqtw==":1,"nf7A+JxA8ON4/SwHof75wg==":1,"d1LPAk7yvo/U79qU6QfZKg==":1,"VhE7mqUPJGPOrUD4YcVmFQ==":1,"yqvrW2ztIjUjNawE6EOSUA==":1,"iaPo13W9l0Kz+YSZsumAmg==":1,"qw26JZ0HcaXGVCMWKpMcxg==":1,"hMt1GoHoquTHnI9ufNoPqA==":1,"SxPABNt8/qIU1p/mv87l2g==":1,"xIuK0MZF7JwtYBNGln+7WQ==":1,"Bt7bigPSaKlWtCnfKPMWNw==":1,"tng3yk/AXqvWgJO2bKdcdQ==":1,"L5zkJa0KRAEjNDE6LF3bBA==":1}

Is this doing it and could I delete it?

The browser.newtabpage.blocked pref stores websites that you have removed from the about:newtab page by clicking the X button.

There is also the browser.newtabpage.pinned pref that stores pages that you have pinned to a tile.