Nothing in the add ons or plug ins
Programmes in control panel is also ok.
I am using windows security essentials and run malware bytes and ccleaner.
I mainly use firefox and it appears to be a problem others have had (google)for various reasons, some say it happened after an update and various recommendations to sort it but nothing has worked, when I set for a blank default opening page it just reverts back when I reopen firefox.
I did try going here which was one suggestion and deleting the value but reverts back although I am wary of changing anything in this section.
I went to about:config
Preference startup.homepage_welcome _url;