Since May last year I am the owner of a 21.5" iMac. A couple of days ago I noticed there was an update and I had let it download. Because it was already late in the evening and the update was quite big, I had let my iMac download it to install it the next morning. The next morning I woke up the screen and pressed install. At some point the installation required an reboot and so I did. Since then I have the problem of my iMac get stuck at the blue screen on startup. However, I still can boot up in safe mode. I am looking for a solution for this problem. I have already tried a few things myself, but they did not help: -Boot in safe mode and reboot -Trying to reinstall OS X, it gives me the error: The installer could not copy the necessary support -Booting with the installation CD and running the disk utility check at the first aid tab of my hard drive. Didn't gave me any errors during process but did not fix my problem -Resetting PRAM and NVRAM -Unplugging all cables and putting them back in If anyone has a suggestion to fix this problem, it would be appreciated greatly. Thanks in advance!