Click on the First Aid tab and select and repair your internal hard disk from the column on the left.

Choose Disk Utility from the utilities window. It should start up with a Menu Bar and a Utilities Window. Restart your computer and hold the Command and R keys while it boots. Check your Disk Utility using the OS X Recovery.Depending on what it finds, you can then determine how to fix the problem using Apple's online support or going to the Genius Bar at the Apple Store. Your system will run a diagnostic test and inform you of any problems.

Turn it on, and before it can boot your desktop, press and hold down the letter D on the keyboard. Run an Apple Diagnostics or Apple Hardware Test (depending on what model you have) to see if anything is wrong with your computer's hardware.If your computer is writing a lot of Page Outs, you may need more memory. Page Outs occur when the RAM is full, necessitating information to be moved from the RAM to the hard drive. Two of the stats you'll see are 'Page Ins' and 'Page Outs,' which describe the information moved between the RAM to the Mac's drive. The System Memory tab will tell you information about your computer's RAM (random-access memory) usage.

Go to your Activity Monitor (you can find it by typing it into the Spotlight).Checking your machine's vitals-RAM, CPU, disk space, and so forth-will keep things running smoothly: Try a Mac cleanup utility such as Mackeeper. How to Stop the Mac Spinning Rainbow Wheel These recurring short freezes are a nightmare for Apple computer users.

Imac spinning wheel on login keychain