How To Clean Your PC From Viruses
A Practical, Step-By-Step Guide From the Techs at Southern Computer Services SA
PC Viruses and other forms of malware slow your computer, steal personal data, and can even lock you out of your files. The good news? With the right approach you can usually remove an infection yourself and get back to a smooth-running system. Below is the exact checklist we use in-house before we escalate a machine to deep-level data recovery.
⚠️ Quick disclaimer: If your data is irreplaceable, if the PC is part of a business network, or if you spot signs of ransomware (file extensions changed, ransom note on the desktop), turn the machine off and call a professional immediately.
Table of Contents
- Signs Your PC Has a Virus
- The 10-Step Virus-Removal Checklist
- Back Up & Disconnect
- Boot Into Safe Mode With Networking
- Delete Temporary Files
- Run Windows Defender Offline Scan
- Scan With a Second Opinion Tool
- Rootkit & Boot-Sector Check
- Manually Remove Suspicious Apps & Extensions
- Clear & Reset Your Browsers
- Fully Update Windows and All Software
- Change Your Passwords
- When You Should Reinstall Windows
- How To Avoid Reinfection
- Need Help? Contact Southern Computer Services SA
1. Signs Your PC Has a Virus
• Sudden slow-downs or frequent crashes
• Constant pop-ups or ads appearing outside your browser
• Unknown programs starting at boot
• Web browser redirecting to strange search engines
• Friends complaining about weird emails or DMs from you
• Antivirus is disabled and won’t turn back on
If you’ve nodded “yes” to any of the above, move on to the clean-up checklist.
2. The 10-Step Virus-Removal Checklist
1. Back Up & Disconnect
- Plug in an external drive or use a secure cloud service.
- Copy critical documents, photos, and project files.
- Unplug the Ethernet cable or disable Wi-Fi. This prevents the malware from phoning home or spreading.
2. Boot Into Safe Mode With Networking
Safe Mode loads Windows with only essential drivers, stopping many viruses from launching.
Windows 10/11:
- Press Win + I → Settings → Update & Security → Recovery.
- Under Advanced Startup click Restart now.
- Navigate to Troubleshoot → Advanced options → Startup Settings → Restart.
- When you see the list, press 5 or F5 for Safe Mode with Networking.
3. Delete Temporary Files
Junk files can hide malicious scripts and also speed up scanning later.
4. Run Windows Defender Offline Scan
Microsoft’s built-in AV can run an offline virus scan before Windows fully loads.
Settings → Update & Security → Windows Security → Virus & threat protection → Scan options → select Microsoft Defender Offline scan → Scan now. Reboot and let it run (15-20 min).
5. Scan With a Second Opinion Tool
Even the best AV misses some threats. Use one reputable on-demand scanner (avoid running two real-time products at once).
Free, trustworthy options:
• ESET Online Scanner
• Kaspersky Virus Removal Tool
Install, update signatures, perform a Full or Threat scan, and quarantine everything it flags. Reboot when prompted.
6. Rootkit & Boot-Sector Check
Stubborn malware can hide in the boot record. Use a specialized tool:
• Malwarebytes Anti-Rootkit (MBAR)
• TDSSKiller from Kaspersky
Follow prompts, remove detections, and reboot.
7. Manually Remove Suspicious Apps & Extensions
Apps & Features:
Settings → Apps → Sort by Install date → Uninstall unknown or recently added programs.Startup Items:
Press Ctrl + Shift + Esc → Startup tab → Disable suspicious entries.Browser Add-ons:
• Chrome: 3-dot menu → More Tools → Extensions
• Edge: 3-dot menu → Extensions
• Firefox: 3-line menu → Add-ons
Remove toolbars, coupon finders, and anything you didn’t choose to install.
8. Clear & Reset Your Browsers
This wipes lingering malicious scripts.
Chrome: 3-dot menu → Settings → Reset and clean up → Restore settings to their original defaults.
Repeat in other browsers, and clear cookies/cache while you’re there.
9. Fully Update Windows and All Software
Viruses often exploit old code.
• Windows Update → Check for updates (install everything, including optional driver updates).
• Update critical apps: Java, Adobe Reader, browsers, GPU drivers, and Office.
10. Change Your Passwords
Do this after the PC is confirmed clean.
- Email accounts
- Banking & shopping sites
- Social media
- Work VPN or cloud services
Use a password manager to create unique, complex passwords.
3. When You Should Reinstall Windows
Sometimes the nuclear option is fastest and safest.
Reinstall if:
• Ransomware encrypted your files
• System files are corrupted beyond repair
• Malware keeps returning after multiple clean attempts
Backup, create a Windows 10/11 USB with the Media Creation Tool, wipe the drive, and perform a fresh install. Install your drivers, update Windows, and restore only clean files.
4. How To Avoid Reinfection
• Keep real-time antivirus ON (Microsoft Defender is fine; paid suites add extras).
• Turn on the Windows Firewall (default state).
• Enable automatic Windows Updates.
• Update third-party software monthly.
• Use a modern browser with phishing protection.
• Hover before you click—especially on email attachments and ads.
• Consider a standard user account for daily tasks; reserve Admin for installs.
• Make regular offline or cloud backups (3-2-1 rule).
“The only truly secure system is one that is powered off, cast in a block of concrete and sealed in a lead-lined room with armed guards.”
5. Need Help? Contact Southern Computer Services SA
If any step feels daunting—or if the infection is still hanging on—reach out! Our certified technicians can:
• Remove viruses, spyware, and ransomware
• Recover lost data and repair Windows without wiping your files
• Install enterprise-grade protection to prevent future attacks
📞 Call us on 0407396188 or email us to schedule a same-day drop-off or remote session.
Stay safe out there, and keep those bytes clean!
© 2025 Southern Computer Services SA – Computer & Laptop Repair Specialists
