Hi   !
This   'other page'   -   is that a page you usually visit, or some page you have never seen before   ?
Hopefully not necessary, but you can try these free programs to scan for malware, which work with your existing antivirus software:
Please scan with all programs because each program detects different malware.
(All these programs have free versions)
• 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
Also see :   Troubleshoot Firefox issues caused by malware

Bookmark and use this; Download the Mozilla Search Reset https://addons.mozilla.org/en-US/firefox/addon/searchreset/

This add-on is very simple: on installation, it backs up and then resets your search preferences and home page to their default values, and then uninstalls itself. This affects the search bar, URL bar searches, and the home page.

Separate Security Issue: Update your Flash Player Note: Windows users should download the ActiveX for Internet Explorer. and the plugin for Plugin-based browsers (like Firefox).

Note: Windows 8 and Windows 10 have built-in flash players and Adobe will cause a conflict. Install the plugin only. Not the ActiveX.

Flash Player Version: 25.0.0.171

https://get.adobe.com/flashplayer/ Direct link scans current system and browser Note: Other software is offered in the download. <Windows Only>

https://get.adobe.com/flashplayer/otherversions/ Step 1: Select Operating System Step 2: Select A Version (Firefox, Win IE . . . .) Note: Other software is offered in the download. <Windows Only> +++++++++++++++++++ See if there are updates for your graphics drivers https://support.mozilla.org/en-US/kb/upgrade-graphics-drivers-use-hardware-acceleration

You can check the target line in the Firefox desktop shortcut (right-click: Properties) to make sure nothing is appended after the path to the Firefox program.

• https://support.mozilla.org/en-US/kb/wrong-home-page-opens-when-i-start-firefox-how-fix