If you think the problem is your hard drive, try these two methods: a) If you have access to another Apple computer, connect the two together via firewire, thunderbolt, or USB cable. Now reboot your computer, holding down the T key as it tries to boot. Your screen should now show the logo of the cable you used, and your computer will show up as an external drive on the friend’s computer. Use their computer to use GET INFO to find out how much space is available on the drive, then delete files as necessary to make more room (after copying them to another drive, if you wish). Finally, use their computer to run disk utility on your computer’s hard drive. Disconnect & reboot. b) Reboot your computer, and hold down COMMAND and R while the computer boots. This will give you access to disk utility on your computer. Select the drive, click on the FIRST AID tab, and select RUN to repair problems on your hard drive.