Thanks to all that have replied. As Orbital Shark suggested I dl'd and am running (even as we type) the Malware program; so far it reports 6 objects infected - but it is still running.
This just in: the malware program finished and reports 14 incidents of malicious software on this system (what the dickens is McAfee doing for me?). I will let that program remove these and see if that solves the problem
James: I do have Firefox installed on this machine but mostly use Chrome. I will, however, do the checks you - and Joelastpass - have suggested.
Thanks to all for your timely replies. I will report back in a day or so to let you know if it is cleared up.