Thanks much. As you can see, there is absolutely no error :( So I guess the only way to fix the symptoms is to install the radeon firmware. If you have never done it before, you need to add the non-free section to your current apt configuration and then install the firmware-linux-nonfree.
Technically this should not be a required step, but that is another story... Ref: https://wiki.debian.org/ATIProprietary#Debian_8_.22Jessie.22 https://packages.debian.org/jessie/firmware-linux-nonfree
