How do you fix a frozen PC or a Mac?

How do you fix a frozen PC or a Mac

Everything comes to a halt the moment you’re going about your day—checking emails or doing some urgent work —and then all of a sudden it does. Your computer becomes unresponsive. You frantically drag and click your mouse in hopes of seeing activity, but nothing happens. Don’t get too worked up.

Our experts assist hundreds of consumers in getting the most out of their technology and resolving its most vexing issues.

Why do computers start freezing or crashing?

For several causes, your Mac® or PC may be crashing:

  • Power or charging issues.
  • Too many applications are active at the same time.
  • An operating system that is no longer maintained.
  • Viruses and/or malware.
  • Overheating.
  • Hardware issues such as wearing out hard drives and or RAM
  • Software problems.

Here’s how to fix your computer if it’s freezing or crashing:

1. Restart your computer

The most common method to repair a frozen computer is to restart it. Doing so allows your system to restart and start fresh. The best technique to restart a frozen computer is to hold down the power button for 5-10 seconds.

Your computer will restart safely without causing a power outage if you do this. Disconnect any external devices since they can cause problems during the reset process of your machine, as it restarts.

If your PC freezes again during startup, though, read further..

2. Force Quit Applications

Force quitting applications is generally the first thing that users try when their computer freezes up or crashes. To force quit an application, simply press and hold down the “Alt” key on your keyboard while you do one of the following: press “Command-Option-Esc” for Mac users; choose “Start Task Manager” for Windows users, or open the Activity Monitor through a Spotlight search under OS X 10.8 Mountain Lion or earlier, or directly from Utilities in OS X 10.9 Mavericks and later. Right-click on an app listed under “Background processes”, select “Quit” to force close it, then repeat this process until all apps are closed out. You can also just restart your computer.

If your computer will not restart, you may have to force a shutdown. To do this with a Mac, hold down the “Shift” key while you click on the “Restart” or “Shut Down” button in the menu bar at the top of your screen. Windows users should press and hold either CTRL+ALT+Delete simultaneously when they see the dialogue box with an option to either log off or shut down; choose shutdown here. Keep holding these buttons until you are met with a window prompting you to turn off or reboot your machine. ____ Now reboot or re-start if necessary.

3. Run a virus scan on your computer

If you have a virus or malware, this may be causing your computer to freeze. A free choice in the list of antivirus/security programs is Avast! Antivirus, which has a free version for home use. If you do not wish to download another program, please try running Microsoft Security Essentials or Windows Defender which comes installed on recent versions of Windows.

4. Unexpected software updates

If a software update caused the crash: Restart your device and press the “down arrow” until you see “Shut Down”. Press “Enter”.

Once your computer is completely off, power it back on by pressing the “power button” located near the bottom of your monitor. After you log in to Windows, check for updates again. You may be able to find a solution just by updating your software. If that doesn’t work, proceed with the next step.

If this happens often: Click “Start”, type “run”, and press “Enter”.

Type “%temp%” into the field at the top of the window that opens up and press “OK”.

Delete any files or folders named “[random letters]*.exe” or “[random numbers]*.tmp”. Press “Save changes” if prompted after deleting these files/folders. Restart your computer.

If this happens occasionally: Press “Start”, type “%temp%” into the search, and press “Enter”.

Delete any files or folders named “[random letters]*.exe” or “[random numbers]*.tmp”. Press “Save changes” if prompted after deleting these files/folders. Exit the window that opens up. Restart your computer.

5. Uninstall conflicting applications

As a last resort (if none of the above fixed your problem): Uninstall Google Chrome, Firefox, Internet Explorer, Adobe Reader, iTunes, VLC media player, AVG anti-virus software if you have it installed on your computer. Restart your computer once all programs are uninstalled successfully. Reinstall these programs one by one to determine which program is causing problems with your computer.

6. Restore your computer to a previous state using system restore or a time machine

System restore on a Windows computer

System Restore is a utility built into Windows to help you restore your computer to a previous state. It works by creating “system restore points” (snapshots) of your computer’s system files regularly so that when something goes wrong with the system, you can turn back the clock and return it to a point before a virus/malware enters your computer.

If nothing else has worked for you, try restoring your computer to a previous state using system restore: Start > Search > Type “restore”: Select System Restore from the list of results. Choose a date before when the problem started occurring on your computer (if prompted): Wait for System Restore to load up: Once loaded, choose Next: Scan through all the dates available on the calendar to find the date that your computer was running smoothly: Select Next: Confirm that you want to restore this system file (click Yes): Select Finish, then wait while the files are restored. When it’s done, try running your computer again. If your problem persists, go to the next step.

How to run a Time Machine restore on a Mac

Before you start, make sure that your computer is plugged in and properly charged.

When you have access to a working Mac, launch the System Preferences application. Click on “Time Machine” which is under a section called “System Preferences”. Select “Open Time Machine”: If necessary, click on Continue: Time Machine will show the most recent backups available. Scroll through them until you find one from before when your computer started having problems: Click on Restore from this backup: Enter your user name and password for the login screen that pops up then click OK: You may need to know some personal information about the state of your system back then (namely, what version of OS X was running).  If so, select Enter Details and fill in some information: You can also check on your system settings and documents using Time Machine.  If you do not need to view them, uncheck the boxes next to System Settings and Documents: After reviewing the settings, select Restore from Backup: When prompted for a location to put the files (and where needed, which version of OS X) back into your computer, choose your hard drive or home folder then click on Select Backup Disk or Folder: The restoration process will begin.

7. Update your Operating System

Update your Windows operating system

If you are running Windows 7 through to Windows 11, Automatic Updates will notify you when new updates are available for your computer. The update notification is a pop-up window. When you click OK, the Update dialog box opens and displays the number of important and optional software updates that are available: Click Install Updates to download and install all available updates. You can also select individual options, such as just installing important updates, only installing critical security fixes, or uninstalling selected patches.

Update your Apple computer

1. Click the Apple logo in the top-left corner of your screen, select “About This Mac” from the menu on the left side of your computer’s window, then click on “More Info.” A new window will open with this information.

2. Clicking “System Report” will generate a list of hardware and software installed on your machine. The first item listed in your system’s Software version; make sure that it matches that of your current operating system. If it doesn’t, there are separate instructions for updating to that particular version here. To update to the latest version, follow these steps:

3. Click Apple in the top-left corner again, then select “Software Update…” from the drop-down menu. Follow the prompts to update your software.

8. Reformatting or reinstalling the operating system

Reinstall your Windows system

If all else fails, you can reformat and reinstall windows if nothing else has worked for you. This will result in all information not saved on external hard drives being permanently erased from your computer; once you format and reinstall Windows, everything on the registry will be reset completely. Delete everything except what is necessary.

When you format and reinstall Windows, keep in mind that your computer will run a little slower after reformatting. That is because the drivers need to be installed again, which not only takes a while but also requires other updates along with these drivers. Make sure that you have all of the software needed before reformatting.

Reinstall your Mac OSX system

First of all, make sure your computer is shut down and you are not installing the operating system on a MacBook. Then turn it on and hold down “Alt” (Option) while you select Disk Utility from the options that appear on the screen. This will open up your hard drive in a new window where you can use the “Erase” tab to delete all previous files. Once you have done this, “Partition” your hard drive and make sure that it is set to the size you desire (however big or small). Once this is done, turn off your MacBook and install the operating system onto the disk you made with Disk Utility.

Now it is time to find your startup disk in the settings. To do this, go into the system preferences and there you will be able to see all of your disks. Once you have selected your startup disk, click on “restore” and select the original macOS that came with your computer. This process may take around an hour but after it finishes, you should not experience any problems with your system freezing or crashing again.

If you are still having issues with your computer freezing or crashing, please contact a computer repair professional.

I am a computer engineer holding a bachelor's degree in Computer Science, complemented by a Master's in Business Administration from University of Strathclyde, Scotland. I currently work as a Senior IT Consultant in Melbourne, Australia. With over 15 years of...