Exact same thing happened to me after installing DP4 (as well as Logic Pro X if that makes any difference).
When I boot without -v, it boots, then right before it goes to the desktop, a white screen appears with the spinning loading icon in the center of the screen. Booting in verbose leaves it at a black screen with a cursor in the top left corner...Wait like 3 minutes and the monitor looses signal and never comes back on...but it's still up and running. I've never seen anything like this before and have no clue where to start with troubleshooting. Has anyone found a solution to this problem?
My specs: GA-H61N-USB3, GeForce GT 630, 4gb RAM, i3-2105
When it's stuck on the spinner unplug your monitor for a few seconds then plug it back in. Tell me if that fixes the issue.