Details also recounted here http://superuser.com/q/1115765/197331
Basically if you set PreferExternalManifests in the registry, mstsc.exe used to run completely fine and machines that you would remote to did not have an insanely high DPI.
Now since the anniversary update, PreferExternalManifests key disappeared from the registry, and if you set it then mstsc.exe just doesn't execute at all. If you run as administrator, you get the UAC dialog asking for permission, but then nothing happens. No process, no events that I can see, nothing.
Any ideas on how either 1) this specific issue could be resolved or 2) any other ways of remoting to other machines with a readable DPI