When I try to open a pdf file a message appears "Adobe Reader blocked for this website". i then click the little arrow and another window pops up and it reads: "Do you want to trus the website www.........com to use the Adobe Reader plug in? And when I click "Trust" I can then move on to my PDF Download. This was never an issue before and wonder how I can rectify this? Does it have something to do with a 'plug in'?