Macbook Pro stuck in boot loop
I tried to reboot my computer; which has been slow ever since I cleaned more than 150 GB of photos off my Macbook Pro (2012) (OSX 10.10) last week. I've been rebooting the computer frequently, as a passive aggressive response to the slow speed, but this evening when I rebooted my computer, I was greeted by this exquisitely inviting little guy. I've never seen this before, and it doesn't look too friendly! Has anyone else experienced this problem, what does it mean, and how'd you fix it?! PS I've tried to reboot twice since then, but it keeps happening again and again.. Any help would be greatly appreciated!! THANKS!
~TC~
MacBook Pro 2012, 13.3", 500 GB Hard Drive, 4GB RAM,
MacBook Pro (13-inch Mid 2012), OS X Yosemite (10.10.1)