I am using Acrobat Pro DC, 2015 release, version 2015.006030121 on a windows 7 pro desk top. When I open a single pdf file I have no printing issues but if I open another pdf file while the original is open (which I need to do quite often and have done so in the past) I can no longer print. The print dialogue window appears, but I cannot print, change properties.printers or anything. If I close all the pdfs down and open a single one again, I can print.
The other issue, perhaps related? Is the original pdf file Adobe icon appears on my taskbar as red bordered black square with the white Adobe symbol. Any subsequent pds opened appear with the icon beside the original as the white "page" one with the red PDF test in the upper left corner and red Adobe symbol,