Reinstalling Lion/Mountain Lion Without Erasing the Drive
Boot to the Recovery HD: Restart the computer and after the chime press and hold down the COMMAND and R keys until the menu screen appears. Alternatively, restart the computer and after the chime press and hold down the OPTION key until the boot manager screen appears. Select the Recovery HD and click on the downward pointing arrow button.
Repair the Hard Drive and Permissions: Upon startup select Disk Utility from the main menu. Repair the Hard Drive and Permissions as follows.
When the recovery menu appears select Disk Utility. After DU loads select your hard drive entry (mfgr.'s ID and drive size) from the the left side list. In the DU status area you will see an entry for the S.M.A.R.T. status of the hard drive. If it does not say "Verified" then the hard drive is failing or failed. (SMART status is not reported on external Firewire or USB drives.) If the drive is "Verified" then select your OS X volume from the list on the left (sub-entry below the drive entry,) click on the First Aid tab, then click on the Repair Disk button. If DU reports any errors that have been fixed, then re-run Repair Disk until no errors are reported. If no errors are reported click on the Repair Permissions button. Wait until the operation completes, then quit DU and return to the main menu.
Reinstall Lion/Mountain Lion: Select Reinstall Lion/Mountain Lion and click on the Continue button.
Note: You will need an active Internet connection. I suggest using Ethernet if possible because it is three times faster than wireless.
Unfortunately it did not work. Disk appears Ok, permissions verified and repaired.
My screen moves horizontally and gets stuck cut in half, frozen, image of desktop or applications look jagged. I have to restart :( I'm not able to do anything for more than a minute.
Could it be a virus?
How do I proceed?
There aren't any viruses. I suggest you go the next step. Backup, erase drive, reinstall:
Install or Reinstall Lion/Mountain Lion from Scratch
Be sure you backup your files to an external drive or second internal drive because the following procedure will remove everything from the hard drive.
Boot to the Recovery HD:
Restart the computer and after the chime press and hold down the COMMAND and R keys until the menu screen appears. Alternatively, restart the computer and after the chime press and hold down the OPTION key until the boot manager screen appears. Select the Recovery HD and click on the downward pointing arrow button.
Erase the hard drive:
1. Select Disk Utility from the main menu and click on the Continue button.
2. After DU loads select your startup volume (usually Macintosh HD) from the
left side list. Click on the Erase tab in the DU main window.
3. Set the format type to Mac OS Extended (Journaled.) Optionally, click on
the Security button and set the Zero Data option to one-pass. Click on
the Erase button and wait until the process has completed.
4. Quit DU and return to the main menu.
Reinstall Lion: Select Reinstall Lion/Mountain Lion and click on the Install button.
Note: You will need an active Internet connection. I suggest using Ethernet if possible
because it is three times faster than wireless.
Option 1: Boot the computer into Single-user Mode then restart normally.
Option 2: Create a new user account with admin privileges. Log out of your account and log into the new account. See if the problems cease.
If you don't want to reinstall from scratch because you do not have a backup, then this would be a good excuse for setting up a backup system and backup strategy.
I'll give it a try, reinstalling Mountain Lion didn't work either, though when I ran again disk utility other permissions showed up for repair.
How do I restore all my stuff if I have to erase the disk, this is such a pain reinstalling programs blah blah blah. I have a back up done with time machine but the computer had problems already.
I have no more time to waste with this I need it running, so frustrating!!
Thanks for your advise
I cannot access DU :( I get a blue screen. How can I move on to finally do what you recommended on the first place: erase the freaking disk. I'm so frustrated! I'm sorry! When I most need my computer it totally fails on me only 18 months old!
Thank you for your help if you are still there. Appreciated it!
Hi Kappy, the problem was not solved. My computer is still crashing, do you know if the disk might be damaged? Even if it says it's OK. Brand new operating system installed after erasing the disk the secure way (took 13 hs), only Adobe Suite CS5 installed, crashing again/blue screen when trying to restart.
What can I do, I'm getting desparate as it is the only computer I have to get work done.