After startup my iMac's screen turns black

Question

My iMac start ups normal. I hear the chime, followed by the apple logo and gears. Then the screen goes black but you can still see the cursor clear as day. I can also turn the brightness up and down, but it is still black. Is there anything I can do to fix it without taking it to the apple store 45 min away?  Please help!!!

Answer 1

Will it start more normally if you choose to hold the Shift key down through startup and then you may be able to see the desktop and login...? This would be SafeBoot mode.
If so, then it could be troubleshooted or console utility logs looked into, to see if there is any evidence of system parts not loading properly, or of a hardware issue. Or a graphics problem after the system loads.
SafeBoot starts the computer in a reduced OS X so several items are turned off.
With an AppleCare plan in effect, you should consider making an appointment
with a Genius at the Apple Store, to take the computer in for diagnosis.
Especially if this repeats itself; that would make it easier to prove a point.
Have you used this computer with an external display?
In safeboot mode, if it starts you could check some other things in the system.
However there are keyboard shortcuts on startup that
may be able to troubleshoot past the problem.
•Intel-based Macs: Resetting the System Management Controller (SMC)
http://support.apple.com/kb/HT3964
•About reset the NVRAM (so you tried it, more than twice?)
http://support.apple.com/kb/HT1379
PS: there may be two things to try:
two workarounds:
Put the computer to sleep (close the lid on a Mac Book (pro) or press the power button quickly on a desktop Mac. After a few seconds of sleeping, wake the computer up again. The login dialog usually appears now.
2. Sometimes you do not want to put the computer to sleep because you do not want to interrupt a task that is running. In this case, press CTRL+SHIFT+EJECT. This keyboard shortcut usually locks the screen. In out case, locking the screen also enables or resets the screen saver, so that the next key press or mouse motion will bring up the login dialog.
Good luck & happy computing!