I put the latest Raspbian-Jessie image on a SD card and popped it in my RPi2, started up just fine, rant the update and upgrade commands then shut the Pi off for the night, tried to boot it this morning and it runs through the normal start up lines then just goes to a black screen with a cursor that occasionally blinks then disappears.

I have a Class 4, 4gig card, is it possible the updates and upgrades exceeded its capacity?