Windows Explorer suddenly stopped showing previews of PDF's, instead I get the message "windows explorer preview "file your are attempting to preview could harm your computer". I have unselected and reselected both the options to turn on the preview pane in windows explorer and Adobe. If I go to the document properties in Windows Explorer, there is an option under security that says "this document came from another computer and might be blocked to help protect this computer "unblock" which I can select and then see the preview in the preview pane but I need an option to unblock ALL PDF's at all times! I don't need Adobe telling me I downloaded a document from another computer, I obviously hit the download button. This is a major time suck to my daily work to continually open PDF's to view them, close them to edit the name, open them to view details again, close to move to a different folder, etc, etc, etc. PLEASE FIX THIS!!