malware pop ups even after a clean install

Going to ssa.gov/benefits/apply for disability on line, on the infected computer pop ups such as Windows 7 Driver updates needed, Life is short Have an affair, and one saying new codec is needed to view webpage. This happens on a computer which before going to to the web page had had a DoD clean and a  clean install of Windows 7 Pro. After reinstalling the workstation the only action done was to check the ssa webpage because that is where this attorney does most of her work. These pop ups are occurring on other computers in the workgroup as well as a Tax and Bookkeeping company across the street. Could these be embedded in the web page? If I go to the same page on my computer, I don't get any od the popups. I haven't run Malwarebytes yet. I am curious as to where these popups are lurking. Any help will be  greatly appreciated.