Hi B,
What web browser program are you using? Have you tried an alternative browser ?
If you don't have these programs on your computers then I suggest that you get them now and run them one at a time and see if your computers have been infected with malware:
http://www.malwarebytes.org/mwb-download/ - the best free malware app on the net! download, install, update and run! (A restart maybe required after you run this program)
http://www.filehippo.com/download_ccleaner - cleans temporary files and other 'rubbish' from your PC..very easy and user friendly!
http://www.fosshub.com/Spybot-Search-and-Destroy.html - another top-notch free Spyware remover..
Let us know how you get on