This started happening a week or two ago and I can't find what setting changed. For, example, When an HTML formatted email message is printed from Outlook, the source is printed instead of the rendered HTML.
A second example is an installer dialog that includes a scrollable text pane with HTML content -- again, It displays the HTML source instead of rendering the HTML. See attached screenshot.
A third example is if a UNC path to an html file is entered into the browser address bar (eg. \\servername\...\default.h
tm), the source is displayed instead of the HTML being rendered. On another PC, under the same circumstances, the html will be rendered properly.