1 Answer

They are not pestering me in e-mail; it just appears on screen when I switch on. Thanks Colleen!

Hmmm, you may have an add on from them then. Go to Tools on your browser and see either extensions or add ons. See if there is something in there that you do not know. Click to disable it. Otherwise, it could be maleware and for that, you need this:
malwarebtyes: http://http://download.cnet.com/Malwarebytes-Anti-Malware/3000-8022_4-10804572.html

1) Download the malwarebytes anti-virus software. (it's free)

2) When you're ready to scan: First delete all cookies and close all open applications and programs.

3) Run deep scan (you might want to do this just before you go to bed as the deep scan can take hours.

4) Quarantine everything it finds.

5) Update malwarebytes each and every time you want to scan your computer. This way you can be sure the software is looking for all known viruses.