I have been deploying Windows 8 laptops for my company using MDT 2012 U1 for a while and everything was fine.
Then just recently I get a completely black screen when users log in for the first time on their newly built PCs and can't do anything. The only thing visible is the cursor. After a long while (about 5 minutes) then Windows wakes up and shows the Start Screen (not all Tiles, though).
The only difference is that only recently I am installing some new Windows Updates. I am now trying to isolate which update causes this and I think it is one of the .NET 4.5 ones.
I noticed that I had a black screen even before the last updates, but it was shown only for a short period of time. After the udpates this period is way longer. I think it is to do with intalling Metro Apps on the Start Screen for the user. Something has changed and the install takes longer. Multiply this for all Metro Apps on the Start Screen and it stays there forever.
Has anybody else noticed this?