I thought that you might be using IE because, purely my opinion, it is Not the best of Browsers and can have compatibility problems with some sites and can depend upon what version of IE that you are using.
It has surprised me that you have tried Firefox and and were given by Mozilla a number of Add-ons which you had not requested. It is possible that they came along with a download which you choose to install from another site.....It often happens and does cause a lot of complications.