Malware infections are one of the most common reasons Windows PCs become slow, unstable, or unsafe. If your computer suddenly starts showing popups, running unusually slowly, crashing frequently, or opening suspicious programs automatically, malware could be the cause.
The good news is that you do not always need expensive antivirus software to clean your PC. Windows already includes powerful built-in security tools, and several trusted free solutions can help remove malware effectively.
This complete guide explains how to remove malware from a Windows PC for free, protect your files, and prevent future infections.
What Is Malware?
Malware is malicious software designed to harm devices, steal information, spy on users, or damage systems.
Common types include:
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Viruses
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Trojans
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Spyware
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Ransomware
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Adware
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Keyloggers
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Browser hijackers
Malware can infect PCs through:
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Unsafe downloads
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Fake software
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Email attachments
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Pirated files
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Malicious websites
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Fake browser extensions
Signs Your Windows PC May Have Malware
Common symptoms include:
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Extremely slow performance
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Random popups
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Unknown programs installed
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Browser redirects
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High CPU usage
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Frequent crashes
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Disabled antivirus software
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Strange network activity
If you notice several of these signs together, malware infection is likely.
1. Disconnect From the Internet
Before cleaning the system, disconnect your PC from the internet.
Why This Helps
Some malware:
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Downloads additional threats
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Sends stolen information
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Communicates with attackers
What to Do
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Turn off WiFi
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Unplug Ethernet cables
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Disable Bluetooth temporarily
This limits further damage.
2. Restart Windows in Safe Mode
Safe Mode starts Windows with minimal drivers and background processes.
This prevents many malware programs from launching automatically.
How to Enter Safe Mode on Windows 11
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Open Settings
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Go to System
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Select Recovery
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Click Advanced startup
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Restart the PC
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Choose:
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Troubleshoot
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Advanced options
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Startup Settings
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Restart
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Press 4 for Safe Mode
3. Run Windows Security Full Scan
Windows Security is already included with Windows and works surprisingly well for most malware threats.
How to Scan Your PC
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Open Windows Security
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Select Virus & threat protection
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Click Scan options
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Choose Full Scan
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Start scanning
Why Full Scan Matters
Quick scans may miss hidden threats.
A full scan checks:
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Files
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Programs
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Startup items
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System memory
4. Use Microsoft Defender Offline Scan
Some malware hides while Windows is running.
Offline Scan Helps Remove:
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Rootkits
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Persistent malware
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Deep infections
Steps
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Open Windows Security
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Go to Virus & threat protection
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Click Scan options
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Choose Microsoft Defender Offline Scan
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Restart and scan
This runs before Windows fully loads.
5. Remove Suspicious Programs
Malware often installs fake or unwanted applications.
How to Check Installed Apps
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Open Settings
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Go to Apps
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Select Installed Apps
Look for:
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Unknown software
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Fake antivirus programs
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Recently installed suspicious apps
Remove anything suspicious carefully.
6. Delete Temporary Files
Temporary folders sometimes contain malicious files.
Use Disk Cleanup
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Search for Disk Cleanup
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Select your main drive
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Delete:
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Temporary files
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Cache files
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Old update files
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Benefit
This also improves PC performance.
7. Reset Your Browser
Malware frequently infects web browsers.
Common symptoms:
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Homepage changes
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Random redirects
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Excessive ads
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Unknown extensions
Clean Your Browser
For Google Chrome
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Remove suspicious extensions
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Reset browser settings
For Microsoft Edge
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Disable unknown add-ons
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Restore default settings
Important
Only keep trusted extensions installed.
8. Check Startup Programs
Malware often launches automatically during startup.
How to Check Startup Apps
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Press Ctrl + Shift + Esc
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Open Task Manager
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Select Startup Apps
Disable suspicious or unknown programs.
Benefit
Prevents malware from relaunching repeatedly.
9. Use Free Malware Removal Tools
Several trusted free tools can help remove stubborn malware.
Popular Free Tools
Malwarebytes
Excellent for removing adware and spyware.
AdwCleaner
Great for browser hijackers and unwanted programs.
Microsoft Defender
Built into Windows and highly effective for many threats.
Important
Only download security tools from official websites.
10. Update Windows and Drivers
Outdated systems are easier to infect.
Update Windows
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Open Settings
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Select Windows Update
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Install all important updates
Why Updates Matter
Security patches close vulnerabilities malware often exploits.
11. Change Important Passwords
If malware may have stolen credentials, change passwords immediately.
Important Accounts
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Email
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Banking
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Social media
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Cloud storage
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Work accounts
Best Practice
Use strong, unique passwords and enable two-factor authentication.
12. Backup Important Files
If your system becomes unstable, backups are critical.
Recommended Backup Locations
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External drives
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Cloud storage
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Secure USB devices
Important Warning
Scan files before restoring them to avoid reinfecting the PC.
When to Reset Windows Completely
If malware remains after multiple scans, a full reset may be necessary.
Reset Options
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Keep personal files
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Remove everything
Best For
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Severe infections
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Ransomware damage
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Persistent malware
Important
Back up critical data first.
How to Prevent Malware in the Future
Avoid Pirated Software
Cracked software is one of the biggest malware sources.
Download Only From Trusted Sources
Stick to official websites and app stores.
Keep Windows Security Enabled
Do not disable built-in protection unnecessarily.
Be Careful With Email Attachments
Never open suspicious attachments or links.
Use Strong Passwords
Weak passwords increase account compromise risks.
Keep Software Updated
Old software often contains exploitable vulnerabilities.
Common Mistakes People Make
Installing Multiple Antivirus Programs
Running multiple antivirus tools simultaneously can slow the system and create conflicts.
Ignoring Browser Extensions
Malicious browser extensions are increasingly common.
Clicking Fake Virus Alerts
Scareware popups often trick users into installing more malware.
Delaying Security Updates
Postponing updates increases infection risk.
Is Windows Security Good Enough?
For most home users, Windows Security provides strong protection when combined with safe browsing habits.
However, users handling:
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Sensitive business data
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Large financial systems
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Enterprise networks
may require additional security layers.
Frequently Asked Questions (FAQs)
Can I remove malware without paying for antivirus software?
Yes. Windows includes powerful built-in security tools, and several trusted malware removal tools are available for free.
Is Windows Security enough to protect my PC?
For many users, yes — especially when combined with safe browsing and regular updates.
What is the best free malware removal tool?
Malwarebytes and Microsoft Defender are among the most trusted free options.
Can malware slow down my PC?
Absolutely. Malware often consumes CPU, memory, storage, and network resources.
Should I reset Windows if malware won’t go away?
Yes. A clean reset or fresh installation is sometimes the most effective solution for severe infections.
Final Thoughts
Malware infections can make a Windows PC slow, unstable, and unsafe, but many threats can be removed completely using free tools and built-in Windows security features.
The most important steps are:
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Disconnecting from the internet
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Running full scans
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Removing suspicious software
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Updating Windows
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Practicing safer browsing habits
Good cybersecurity is not only about antivirus software — it also depends on smart online behavior, regular updates, and cautious downloading habits.
With the right approach, you can keep your Windows PC secure, fast, and malware-free without spending money on expensive security software.