I just ran into same problem. Looking forward to official fix.
My poor workaround is:
Login and get black screen
Move mouse until cursor shows up
Cntrl alt del
Choose task manager
From task manager right click on any file and choose open file location: this opens file explorer
From file explorer you can open and run programs but how to get desktop???
From file explorer choose desktop
At this point I don't know what I am doing; I hover and right click various thing such a restore, New folders properties without doing anything. Last time I clicked view and open options and the desktop appeared.
Once you get in open settings and select update and security and choose recovery. Go to advanced startup and restart now.
After restart >troubleshoot >advanced options >startup settings >restart. When it restarts you can choose safe mode or mess with start up.
Not sure if mine is fixed or not. I have surface pro 3 and thought it might have something to do with tablet mode but doesn't look like it.
Hope this helps. At least you should be able to run programs.
Edited by hamluis, 11 August 2015 - 03:49 PM.
PM sent new OP - Hamluis.