Ok, so i was looking for hours to find the answer to this. I tried it all. I hunted through about:config, I tore apart everything that looked like an addon from MSFT, I tried it all. So then i just on a whim tried........well the basics of the internet.

See if it works for you.

Click new tab button. Should bring up the "bingbar", or some sort of Bing hijack. Right click anywhere in the page. Click at the bottom "view page info". At the top of the window that opens, there is "address". It then tells you the heart of the page. mine happened to read "chrome..........". When I saw it I knew immediately that it was an extension in my addons. When I saw it in my addons though, as it starts with CHROME, I assumed it was a google chrome extension. Low and behold it was a new MSFT. ef u.

So give er a try and see if it helps you to locate your source of anal misery.

My problem came from "Flash Video Downloader" plugin I had installed. It decided to put a nice little toolbar on my FireFox so once I disabled the toolbar I was able to open tabs without Bing getting in the way.

Now the toolbar is gone but my function to download videos went with it, but the workaround is that I just went to view>toolbars>customize and then I just dragged the FVD icon next to my search bar.

If I disable all add-ons and plugins and restart Firefox, the Bing problem goes away. However, when I restart my computer, it comes back even though Firefox claims that all plug-ins are disabled.

Most likely, it is an issue with an add-on. Sometimes, this happens with automatic updates and the like. Go to your add-on manager and look at your extensions. If you see a toolbar that you didn't specifically authorize, disable it or remove it and see if that solves the problem. I know that this issue happens with people who download utorret (and often download the utorrent toolbar by mistake).