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John T. F.
John T. F., Mac Druid
Category: Mac
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Experience:  20+ years in the computer/Mac industry
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imac freezes on startup.Command R worked the first time around,

Customer Question

imac freezes on startup.
Command R worked the first time around, then after several days and a couple of reboots the imac began freezing on startup. (Radian stopped spinning, and the white apple screen briefly flickered)
On the second freeze on startup. The command R did not work. But the Reset of the PRAM did work.
This time we repaired a directory that wasn't reading, and the iMac ran well for several days a couple of reboots.
Now, for the third time, the iMac freezed on startup. The Radian freezes on the white apple screen.
Command R does not work.
PRAM reset does not work.
D (hardware test) does not work.
C (boot from drive) attempts to boot, but freezes, and after 30 minutes remains frozen.
Your thoughts please.
Submitted: 4 years ago.
Category: Mac
Expert:  John T. F. replied 4 years ago.
Hello! My name is John, I will work diligently to provide accurate advice and information.

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Lock ups such as this often indicate hard drive issues. Since the standard Recovery is not working well for you currently, see what internet recovery will do:

Shutdown your Mac.

Restart and, as soon as you hear the startup chime, hold COMMAND + R + OPTIONS keys until you see the Apple logo and progress indicator.

Wait for “OS X Utilities” menu to appear (DO NOT CHOOSE TO INSTALL)

Choose Disk Utility from the available options.

In Disk Utility, select your normal, bootable hard drive volume from the list in the sidebar (usually "Macintosh HD").

Then, Click "Repair Disk"

If it finds errors, repeat the process until it reports the drive is OK.

Next, click "Repair Disk Permissions"

Then, restart your Mac and see if it will boot back into your normal Desktop.

If that does not work or there still seems to be issues;

Power off the iMac.

Unplug the iMac's power cord.

Wait a minimum of fifteen seconds.

Attach the iMac's power cord.

Wait at least five seconds, then press the power button to turn on the Mac back on.

See if there is any improvement.

If you continue to have questions on this topic, just reply back to this discussion. I will be more than happy to work with you further. Hopefully, this info will answer your question. If so please, please remember that when you are asked to give a rating, you are rating my personal service only and not this website itself or your issue.

Thanks and good luck,
Customer: replied 4 years ago.

The Options Command R brought up the Radian icon, but not the progress bar. The computer froze again.


We then followed the final instructions to unplug and reboot. Freezing again on boot up.

Expert:  John T. F. replied 4 years ago.
Please perform the PRAM reset procedure, this time holding the keys down until the chime sounds THREE times and then immediately power off the iMac.

Restart and try Command + R + Opt once again.

Customer: replied 4 years ago.

Hi John,


We restarted the iMac, pressing Command + Options + p + r on startup (At first chime). Shortly after there was a second chime. Then the Radian froze. We kept the four keys held down and the apple logo and Radian disappeared, leaving us with a white screen, and nothing else.


Your thoughts please.

Expert:  John T. F. replied 4 years ago.
On previous attempts to use Disk Utility to to verify/repair the drive, did it repeatedly indicate any issues? You mention repairing a directory.

Customer: replied 4 years ago.

Our previous attempt on checking the harddrive, found that one out of the thirty directories was defective?

The repair was initiated, and the drive verified. That was all good. There were no other issues at that time.

There were no repeated issues.

Expert:  John T. F. replied 4 years ago.
Did this iMac originally ship with OS X Lion/Mountain Lion?
Customer: replied 4 years ago.

Sorry for the delay, I didn't realize you had already responded...


The Mac OS X Snow Leopard appears to the the original, and I have that disk in my possession right now.

Expert:  John T. F. replied 4 years ago.
Ok for troubleshooting purposes, are you able to boot from it?
Customer: replied 4 years ago.

No, we haven't been successful booting from the disk tonight. Booting the iMac, while holding the C button,will spin up the optical drive, but after 30 minutes the white screen remains and everything stays frozen.

It does appear that the iMac is trying to read from the optical drive, but after about 5 minutes, the optical drive goes silent.

Expert:  John T. F. replied 4 years ago.
If you restart and hold down the OPTION key does it even provide a listing of bootable volumes?
Customer: replied 4 years ago.

Yes, it shows the icon for the Macintosh HD

Expert:  John T. F. replied 4 years ago.
...but does not show the Recovery HD volume or the OS X Snow Leopard install disc?

Customer: replied 4 years ago.

Sorry John,


The boot screen shows the MacIntosh HD and Mac OS X Install DVD,

but that is all. There is not Recovery HD volume available to us.

Expert:  John T. F. replied 4 years ago.
Alright Steve,

going by everything you've indicated to me and the behavior of the iMac, I think all signs are pointing to a physical hardware issue. Sometimes, the file system of the hard drive can become corrupted to the point that booting is difficult but it doesn't sound like Disk Utility found very much to worry about AND the inability to boot from the CD, as well, would point toward something a little more serious.

The repetitive, intermittent nature of the issue might point directly to a failing hard drive in this case.

This is not a user repairable issue for most people unless you are comfortable working with the innards of your iMac and would necessitate service by an Apple authorized repair center. If you'd like I can try and point you toward the nearest location though a listing should be available here:

Customer: replied 4 years ago.

Hi John,


It seems that the HD is not working, but shouldn't we be able to boot from the Optical Drive using the OS X disk? It seems odd that the iMac spends upto 5 minutes accessing the optical drive, but then eventually freezes while remaining on the white screen. But there is still some optical drive activity every minute or so...

Expert:  John T. F. replied 4 years ago.
Depending on the type of failure, the defective hard drive might not be communicating with the system properly and during the boot process the iMac can see the hard drive and sends a "hello", so to speak, but never receives a response or receives gibberish confusing things. If the hard drive was dead outright, the system would likely boot very quickly from the optical drive.

The failure may also not be directly with the hard drive but somewhere else along the chain, as well, but in most cases the drive is at fault.

Customer: replied 4 years ago.

Thanks for your help. Good night...

Expert:  John T. F. replied 4 years ago.
You are very welcome!

If you have any further questions, don't hesitate to ask at any time.

Expert:  John T. F. replied 4 years ago.

I'm just following up with you to see how everything is going. If you need further assistance on this or other issues, please let me know.