I think this may be because I ran out of memory.
I think you mean hard drive space. Memory is RAM which determines the speed of your computer.
How large is your hard drive?
MacBook Pro (15-inch, Mid 2010): Intermittent black screen or loss of video. Affected computers were manufactured between April 2010 and February 2011.
Thank you for responding. Here's some info about my computer: OS X, 320GB 5400-rpm hard drive, 2.66GHz Intel Core 2 Duo processor. I checked out the links and I don't think they apply. I do some sports videoing and download into IMovie. I downloaded a particularly large video & was trying to copy it to a cd when my computer became very slow. I was trying to delete some files hoping to free up some space but now it's just black.
If Intel-based Macs: Resetting the System Management Controller (SMC) nor Resetting your Mac's PRAM and NVRAM do not work call Apple tech support if you are still under warranty. Otherwise, take the computer to an Apple store or an AASP. Whichever is more convenient for you.