Alienware Area 51 boot problems

I've searched other threads and forums for similar issues and while other people's problems do have some similarities, the experience I'm having seems somewhat unique.  

The issue started after upgrading to Windows 10 (the upgrade was successful, no issues) and has been happening periodically ever since I completed the upgrade a little over a month ago.  I have dual Nvidia GeForce GTX 970 video cards.  When starting the PC, the Alienware text will appear on the screen, then the monitors go black and I have no mouse cursor.  The screens just sit there until the Windows log on screen eventually comes up.  This takes anywhere from 5 to 30 minutes.  Once the log on screen does finally appear, I'm able to log in and everything functions normally.  This doesn't happen on every single startup, but I'd say at least 1/3 of startups result in the black screen.

If I'm feeling impatient, I can force a shutdown (holding the power button) and power the PC back on.  It never hangs at the black screen on the second power up.  Ive kept up to date with driver updates, etc. so I'm at a bit of a loss on how to resolve it.