The mouse may stop moving while the keyboard still seems to work.The mouse and keyboard stop working, and all windows are frozen.You can’t close any open windows or applications.The entire screen turns blue and displays an error code.

Your Mac or Windows computer can freeze unexpectedly, and sometimes the cause isn’t very obvious or easy to troubleshoot.

Cause of a Frozen Computer

The most common cause of computers freezing is software-related. It might be software that’s incompatible with your system, an app that’s stuck in a loop, corrupt files like faulty device drivers, or a virus or malware writing to protected system memory or overwriting sensitive system files. Another possible cause is damaged hardware like a damaged hard drive or failing memory cards. If failing memory contains any OS-related boot code, the computer might not only freeze but could potentially not boot back up either.

How to Fix a Frozen Computer

Below are general troubleshooting steps you can try regardless of the operating system. Start with the first steps for quick fixes that help most of the time when a computer freezes. Troubleshooting gets more advanced as you work down the list. If closing any application allows your computer to work, you may want to consider uninstalling the application, so your computer doesn’t freeze again.