xxxxx

It could be the work of one of your add-ons, or even add / mal-ware.

Type about:addons<Enter> in the address bar to open your Add-ons Manager. Hot key; <Control>(Mac:<Command>)<Shift> A)

In the Add-ons Manager, on the left, select Extensions. Make sure you know what each one is and what it does.

Some added toolbar and anti-virus add-ons are known to cause Firefox issues. Disable All of them.

Also, check the programs that are on your computer

Windows: Start > Control Panel > Uninstall Programs. Mac: Open the "Applications" folder. Linux: Check your user manual.

Go thru the list. If you find something that you don't know what it is, use a web search.

Troubleshoot Firefox Issues Caused By Malware {web link}

mac

Possible Mal-Ware Scan For Macs {web link}

Type about:preferences#general<Enter> in the address bar.

There are two settings;

• When Firefox Starts

When the browser is started, what do you want to display. Many of us choose Show My Home Page.

• Home Page

When a new page is opened, what do you want displayed.

1. Use Current Page. Use what ever page(s) are open at that time.
2. Use Bookmark
3. Restore To Default. about:home shows a Mozilla home page with tools.

You can use any of these that you wish;

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 or about: page you want.

If that is a search page - see this - http://malwaretips.com/blogs/search-ividi-org-virus/