I agree with Marcus. You have been probably been hijacked. e.g. about:search was a common and persistant hijacker to remove.
In the interim you can pop up your browser internet options and change your home settings to anything. Whilst in your browser, select a reliable page e.g. www.bbc.co.uk Then enter your browser and set your home page to the current page.
But, use Google to search for protection against this hi-jacking.