Why is my computer freezing and locking up?

A computer that freezes or locks up can be incredibly frustrating. When you’re in the middle of working on something and the computer just stops responding, it can make you want to pull your hair out! There are various potential causes for a computer freezing or locking up, ranging from software issues to hardware failures.

What exactly does “freezing” and “locking up” mean?

When we say a computer “freezes” or “locks up”, we mean that it becomes completely unresponsive to input. The mouse and keyboard stop working, clicks and key presses do nothing, and the computer screen typically stays stuck on whatever it was displaying when the issue started. A frozen or locked up computer will remain in that state until something forces it to restart, like holding down the power button or unplugging it from the wall.

Common causes of computer freezing and lockups

Too many programs and processes running

One of the most common reasons a computer might freeze or lock up is simply because it has too much going on at once. If you have dozens of browser tabs open, several programs running simultaneously, and a bunch of background processes and apps taking up resources, it may be more than your computer can handle.

When the CPU, RAM, hard drive, and other components become overburdened, they can’t respond quickly enough to keep things running smoothly. The system grinds to a halt as it struggles to keep up. Closing unused programs and tabs can help prevent freezes related to overloading the computer’s capabilities.

Malware, viruses, and other malware

Malicious software like viruses, Trojans, spyware, and ransomware can also cause your computer to freeze or become unresponsive. These types of infections can happen if you click on bad links, download suspicious files, or visit compromised websites.

Malware runs secretly in the background, using up CPU cycles and memory space as it does things like mine cryptocurrency, record your keystrokes, or encrypt your files. All that activity can bog down your computer and lead to freezing or crashes. Antivirus software is essential for catching and removing infections.

Faulty software and drivers

Sometimes there are bugs in a piece of software, the operating system, or hardware drivers that cause conflicts and crashes. Unstable, unoptimized, or incompatible programs and drivers are a common source of computer lockups and freezes.

Updating to the latest software and drivers can often resolve issues caused by bugs. If a particular app always seems to freeze your computer, uninstalling it and finding an alternative may help. Keeping your operating system, browsers, and other software updated is good preventive maintenance.

Overheating hardware components

If components like the CPU and GPU overheat due to issues like a failing fan or blocked ventilation, they can start malfunctioning and lead to freezing. Overheating can also cause hardware damage over time.

Check that your computer case fans are running and make sure vents aren’t clogged with dust if you suspect overheating may be the culprit. A cooling pad can also help laptops stay cool under heavy loads. Reapplying thermal paste between the CPU and heat sink may help an overheating desktop or laptop.

Failing RAM and hard drive issues

Unstable, failing, or incorrectly seated RAM sticks can manifest freezing, crashing, and blue screen errors. Faulty hard drives can also lock up the computer if they have bad sectors or mechanical issues.

Run memtest to check your RAM for errors. Hard drive health can be monitored with tools like CrystalDiskInfo. If either component is showing signs of failure, replacement may be necessary.

Power supply unit failures

If the computer’s PSU (power supply unit) starts to fail, it can cause all sorts of freezing, crashing, and stability issues. One sign of a failing PSU is random shutdowns or the computer powering off suddenly without warning.

A low-quality or underpowered PSU that’s overwhelmed by your hardware can also cause problems. Verify that your PSU can provide enough consistent power for the components you have. Replace or upgrade the unit if needed.

Other hardware problems

Defective or disconnected internal components like the CPU, motherboard, graphics card, and storage drives can sometimes be the culprit behind computer lockups. For example, if the CPU fan becomes disconnected or stops working, it will quickly overheat and malfunction.

Issues with the motherboard, RAM, hard drive, and power supply can cause freezes and crashes too. Diagnosing faulty hardware often requires testing components in a different computer to isolate the problem.

How to determine the cause of a computer freeze

When a computer freezes, it’s not always immediately obvious what made it happen. However, there are some steps you can take to help determine the underlying cause:

Check Task Manager

Task Manager in Windows provides details on current system resource usage. Look at the Processes, App history, Startup, and Performance tabs to see if anything looks unusual.

  • Is the CPU, memory, or disk at very high utilization?
  • Are there any unfamiliar processes or startup items?
  • Does the system resources usage align with what programs are currently open?

This can provide clues on any software-related causes. You can also try ending suspicious processes to see if it fixes the issue.

Check event logs

Event Viewer on Windows keeps detailed logs of warnings, errors, and other system events. These can indicate the source of problems like freezes and crashes.

Look for critical errors around the timestamps of computer freezes. Errors from sources like the kernel, hardware/drivers, applications, and Windows failures often indicate issues.

Update all software

Make sure Windows, drivers, browsers, and all other apps are fully updated. If the freeze is caused by a buggy version of software, updating could resolve it.

Scan for malware

Run a full antivirus scan to check for any infections. Quarantine or delete anything dangerous the scan turns up. Malware removal may stop freezes caused by malicious programs.

Check temperatures

Use hardware monitor software like Speccy or HWInfo to check component temperatures. Consistently high CPU, GPU, or hard drive temperatures may indicate cooling or thermal paste issues.

Test hardware configurations

If the cause isn’t obvious from software checks, try testing different hardware configurations. For example:

  • Boot with each RAM stick individually to isolate bad modules
  • Remove non-essential peripherals and expansion cards
  • Try a different graphics card or using integrated graphics
  • Test hardware in another computer if possible

Narrowing down which piece of hardware may be faulty can help identify failures causing lockups.

Check reliability history

Reliability Monitor on Windows keeps track of system stability and failures over time. Lots of hardware, Windows, or application errors could indicate broader issues.

How to recover from a frozen system

When your computer completely locks up, there are ways you can attempt to regain control:

Use Task Manager

If you can still move your mouse, quickly open Task Manager (CTRL+Shift+Esc) and go to the Processes tab. Try ending any unresponsive apps or processes.

Restart Explorer

If Task Manager opens but you can’t access desktop icons or the Start menu, restarting Windows Explorer may help. Go to File > Run new task and enter “explorer.exe” to reopen Explorer.


Rapidly press the ALT and TAB keys together to cycle through open windows. This may force a stuck window to redraw.


The CTRL + ALT + DEL keyboard shortcut opens a menu with options to open Task Manager, lock the computer, switch users, and restart the system. This key combo may work even when the system is mostly unresponsive.


REISUB is a sequence of keyboard shortcuts designed to gracefully restart a frozen system. It stands for:

  • R – Switch to Raw input/output mode
  • E – Terminate processes
  • I – Kill programs
  • S – Sync disks
  • U – Unmount drives
  • B – Reboot

Press each key sequentially to try forcing a reboot. This is less abrupt than just powering off.

Force power off

If nothing else works, hold down the power button until the computer shuts off. This hard resets the system without going through a proper shutdown sequence.

For computers that don’t have a power button you can press, you may need to unplug the machine or switch off the PSU.

How to prevent computer freezes and lockups

To help avoid frustrating system freezes and crashes in the future:

Close unused programs

Don’t keep apps and browser tabs open if you aren’t actively using them. The fewer programs running simultaneously, the less likely overload freezes become.

Check for malware regularly

Prevent malware infections by being cautious when downloading files and visiting unfamiliar websites. Scan your system with antivirus software regularly.

Keep software updated

Outdated apps and operating systems are more vulnerable to bugs and security flaws. Promptly install all updates for software and drivers.

Clean out dust and pet hair

Open up your desktop tower or laptop casing and use compressed air to clear out ventilation intakes blocked by dust buildup, which can cause overheating.

Don’t overload outlets

Plugging too many PCs and accessories into one outlet can cause electrical issues leading to freezes. Use a power strip with surge protection.

Replace failing hardware

If you suspect hardware components like the RAM, hard drive, motherboard, or PSU are failing, replace them before catastrophic failure causes freezing.

Upgrade outdated components

Improving aging or underpowered hardware like the CPU, RAM, graphics card, or storage devices can prevent freezes related to overwhelming outdated components.

Cause How to Diagnose How to Fix
Too many programs running Check Task Manager for high usage Close unused apps and browser tabs
Malware infection Scan with antivirus software Quarantine or remove malware
Faulty software/drivers Check event logs for application errors Update software and drivers
Overheating components Monitor temperatures with hardware software Improve airflow and heat dissipation
Failing RAM Test sticks individually for errors Replace faulty RAM modules
Hard drive issues Check S.M.A.R.T. status with CrystalDiskInfo Replace malfunctioning hard drive
Faulty power supply Test with multimeter or alternative PSU Replace unreliable or underpowered unit
Other failing hardware Try components individually in a working PC Swap out malfunctioning parts


Computer freezes and lockups can stem from a range of issues like software conflicts, malware, overheating, faulty components, and more. By understanding the various potential causes and how to diagnose them, you’ll be better equipped to pinpoint and address what’s making your system freeze up.

Prevention is also key – keeping software updated, clearing dust buildup, and replacing aging hardware before it fails can go a long way towards avoiding freezes in day-to-day use. But if your computer does lock up, techniques like Task Manager, REISUB, and forced reboots allow you to recover control.

With the right mix of preventive maintenance, performance monitoring, and troubleshooting techniques, you can minimize frustrating system freezes and keep your computer running smoothly.