iMac 27" Screen goes black screen My iMac 27" screen went black on start up after logo, but I could still see my mouse pointer. I've restarted my computer and it is still not helping at all.

I'm running Mavericks 10.9.2 with an i5 processor and 4GB RAM.

Couple things that I've done:


I did a PRAM reset with ⌘, ⌥, P &amp; R at start up and still no luck.
Launched Disk Utilities by holding command &amp; R keys at start up, ran disk diagnostics and got a good message. I also click all repair related buttons and still green message appeared OK.
I booted up into Safe mode and still no luck.
I ran Apple Hardware Testing and the result is good.
I've reinstalled OS X Mavericks and still the same problem.


I'm wondering what would be the possible culprit with this kind of issue?
I've ran into this issue a couple of times now, this is what has resolved the issue each time. Step 5 sometimes returns a "file not found" error and step 6 doesn't always seem to be necessary but has been in some cases.  Regardless, having in their doesn't seem to have an negative effects.




Boot to single user mode (hold ⌘ S while powering on the Mac)
Type and hit return: /sbin/fsck -fy
Type and hit return: /sbin/mount -uw /
Type and hit return: rm /Library/Preferences/com.apple.loginwindow.plist
Type and hit return: rm /Library/Preferences/loginwindow.plist
Type and hit return: rm /private/var/db/.AppleUpgrade
Type and hit return: reboot


Assuming all instructions were followed the Mac should reboot and reach the login screen with no trouble.  The instructions above should be followed VERY carefully, with attention paid to spelling and spacing, as there aren't many safeguards in single user mode to prevent you from deleting otherwise necessary files.

If you have access to another Mac and a Firewire/Thunderbolt cable you could boot this Mac in Target Disk Mode ( T while powering on) and connect it to the spare Mac to remove the files from the GUI.  You would need to open the iMac's system volume (default is Macintosh HD) and remove or rename the two files mentioned above in Library/Preferences.

Hopefully that helps!