Macbook problem: each time I start my computer, I get black progress line. When it finishes I get message " You shut down your computer because of a problem" With the options Cancel or open. Then regardless computer shuts down. Any thoughts?

Each time I start my MacBook, I get black progress line. When it finishes loading I get the message ” You shut down your computer because of a problem” With the options Cancel or Open.  Then regardless of what I do computer shuts down after about a minute. Any thoughts?

Before this started happening I received messages about not having enough disk space for start up disk and I deleted several gigs of files.

Thanks for your thoughts.

OS X Yosemite 10.10.3