How To Fix Blue or Grey Screen on Startup On MAC OSX

Like any computer, a Mac is prone to serious problems over the course of its life. A wide variety of things can go horribly, horribly wrong. From a complete failure to start to that terrifying kernel panic screen, here's how to troubleshoot (and hopefully fix) what's plaguing your Mac.

Fix Blue or Grey Screen on Startup On MAC OSX

When you turn on your computer and get a grey or blue screen or it gets stuck at the Apple logo that never loads OS X, it's a pretty good cause for concern. This can happen for a number of reasons, so it's one of the most frustrating things that can happen to a Mac, and troubleshooting it is no easy task. Here we discuss some simple steps to fix it. 

1. Disconnect All Peripherals

One of the main causes of a grey or blue screen on startup is incompatible hardware connected to the machine. This might be a printer, an external hard drive, or even a USB hub. So, disconnect everything except the mouse and keyboard, and restart your computer.P

If your Mac starts this way, then it's an issue with one of those peripherals. You have to trial-and-error your way through to figure out which one, so connect them back into your computer one by one, and restart.P

If you figure out the problematic peripheral, it's time to do a little research. Head to the manufacturer's web site and see if others are reporting the same problem. You might be able to fix it with a software update or a firmware update to the device.P

If no devices are causing problems, and your Mac still won't boot, then we need to move to another step.

2.  Perform a Safe Boot

Safe boot makes your Mac boot up with the minimum amount of drivers needed to make it work, and it checks your hard disk in the process. It may take some time to startup. To do this, start up your computer while holding down the Shift key until the Apple logo passes. If your Mac starts up with the safe boot, go ahead and restart the computer again and see if it boots up normally. If still its not fixed then its time for more trouble shooting steps.

3. Run Disk Utility

• Boot up your computer while holding down Command+R (if you're running Snow Leopard or earlier, find your OS installation disc, put it in the drive, and reboot your computer holding down C). This will boot you into a diagnostic mode.

• Select the Disk Utility Option.

• Select your hard drive, and click "Verify." Wait for Disk Utility to finish running.

• If problems pop up, click "Repair Disk."

• If nothing pops up, click "Repair Permissions" and wait for Disk Utility to scan your hard drive again.
• Disk Utility finds and repairs some problems, go ahead and reboot.In a lot of cases, running Disk Utility will catch problems with startup issues. Sometimes a single file with the wrong permissions can cause the whole system to collapse, or if something's not in the right place it won't boot. If still issue persists then there is some thing wrong with the hard drive.