Hi
I am having the same issues, which started yesterday, firstly on mac rumours, then ebay and this morning John Lewis website. I am currently running Mavericks 10.9.5 and can't upgrade my OS as I also have the issue of software and hardware no longer working. I saw on one forum about installing Avast antivirus software, but some say this will affect the system, so I didn't proceed. When I check in safari preferences privacy, there is no cookies for either stags or bluekai, so no option to remove them. When I get the drop down security certificate, I click cancel, which is possibly why it doesn't appear, but am not sure if this affects the running of the sites.
I see that another user suggests empty caches (not sure how) and you suggest installing Disconnect. Will Disconnect affect the running of the machine, as in antivirus software? Have tried John Lewis site on firefox and seems to be OK, so much be a safari issue.
Any help gratefully received as am starting to get fed up with constant drop down window. Thanks