The customer’s iMac, desktop computer, started to display a color spinning color wheel on the display and the user could not perform any computer activity. There are a number of almost secret Mac utilities one can very easily employ to try to fix these problems. Let’s go down the list as I had to do to find a fix for this computer. My list order can be changed. The order I show here can be changed. My point is to try them all until the computer is fixed.

#1 I reset the non-volatile RAM (NVRAM) using Macworld procedures outlined below (my changes included):

To reset your NVRAM, you use exactly the same procedure you once used to reset PRAM.
Shut down your Mac.
Press the power button, and as soon as you power up the laptop, hold down Command-Option-P key and -R key.
Keep holding down those keys until you hear a SECOND chime.  For me this took a long, long, time.  After you hear the second chime then let go of all the keys and allow your Mac to continue starting normally.  The startup process for me took some time.
Then check the Startup Disk, Display, and Date & Time panes of System Preferences to make sure they’re set the way you want them.
If you hold down Command-Option-P-R at startup and you see nothing but a gray screen that doesn’t change for several minutes—no Apple logo, no progress bar, no second startup chime—don’t panic. The most likely cause is that your Mac isn’t registering the key presses due to wonkiness with a USB device. Disconnect all USB devices (except your keyboard, if it’s a wired keyboard), hold the power button down until the Mac shuts off completely, and then press it again and immediately hold down Command-Option-P-R.

#2 I reset the System Management Controller (SMC)
Before you can reset your SMC, you must shut down your Mac. After that, the procedure varies depending on the type of Mac you have.
Desktop Macs: Disconnect the power cord (either from the Mac or from the AC outlet). Wait 15 seconds and plug it back in. Then wait another 5 seconds and turn the iMac back on by pressing the power button for 8 seconds or more.

#3 Safe Boot:
I performed the safe boot.

• Press and hold the Shift key immediately after you hear the startup tone.
• Release the Shift key when the Apple logo appears. Safe Boot appears on the Mac OS X startup screen.
• Failure to solve the problem but this allowed me to launch Disk Utility and Activity Monitor (shown below).

#4 Disk Utility:
I ran the disk utility and it showed nothing wrong with the hard drive.

#5 Activity Monitor

I got the computer to run for a short time so I launched Activity Monitor. This application can be found in Applications > Utilities. When it is launched it can appear quite intimidating. A long list of current computer activities is shown with the most demanding activity listed at the top and boy does the list constantly change. The trick is to concentrate on the top list of items because they use the most computer time/resources. Instantly I spotted “Backup” being the top list item. That did NOT make sense to me.  I was not running any backup application.  I double clicked on that task.  A window appeared on the screen showing that task information.  From that window I selected “Quit” option. The computer began to work way better.

#6 System Preferences

I then went to the computer “System Preferences” and mouse clicked on “Users & Groups”. I mouse selected the customer’s “Current User” name. I then mouse selected “Login Items” and found that the “Data” hard drive appeared. That is WRONG!  There is NO computer application called “Data”.  I mouse selected “Data” and mouse clicked the negative or minus icon to delete that start up item.

#7  Time Machine

I went to view the Time Machine settings and found that the customer had chosen to backup “Applications”.  In my opinion, this was a mistake.  You typically want to backup your data such as documents, pictures, movies, etc.  I removed Applications as a backup.  To really make sure the customer’s computer was working, I turned Time Machine off.  Let’s see how the computer works for a week or two.

The computer worked quite well after these changes.

 

Revised:  8/24/2022.  Removed web page links because they were broken.