How to Check If Your PC Has a Virus | PremiumAV

A slow laptop can make an ordinary workday frustrating, but slowness alone does not prove that a virus is present. A nearly full disk, an unfinished update, too many startup apps or failing hardware can produce similar symptoms. This guide helps you collect useful evidence and carry out sensible checks before deleting files or paying someone to fix a problem you have not identified.

The focus here is diagnosis and deciding the next step. If an antivirus has already detected malware, use our malware removal guide. If files are suddenly being renamed or encrypted, disconnect the PC from its network and seek help immediately rather than spending time on routine performance checks.

Start with the warning you can describe

Write down what changed, when it started and what you were doing beforehand. Examples include repeated redirects in one browser, a new application you did not install, security settings that switch off, or messages sent from an account without your knowledge. A screenshot of a warning can help support staff, but exclude passwords, licence keys and private customer information.

Be cautious about warnings displayed inside a web page. A page claiming that your entire PC is infected may be an advertisement or a scam. Do not call a number shown in a surprise alert, install its recommended cleaner or grant remote access. Close the tab using the browser controls. If the tab will not close, close the browser normally or use Task Manager to end that browser process.

Check the protection application first

Open your installed antivirus from the Start menu or its known tray icon, rather than from a link inside a warning. Read the protection and update status. Confirm that the application is running and check the date or status of its most recent update. An update failure is something to investigate; it does not by itself establish an infection.

Windows Security can show which antivirus provider is active. Search Start for Windows Security, open Virus & threat protection and inspect the provider information available on your PC. The controls shown vary with the installed software and your administrator's policies. Use your active provider's application for scans and repairs. Do not disable working protection to follow an unfamiliar tutorial.

Update and run a scan

Save your work, connect a laptop to power and update the active antivirus through its own interface. Run a quick scan first if that is the recommended initial check. Read the completion summary and any detection history. If symptoms persist, choose a full scan or the provider's documented deeper scan. Large disks and archives can make this take time.

If the scanner reports a threat, record its name, file location and recommended action. Use quarantine when offered instead of manually opening or emailing the detected file. Do not restore it simply because it appears to belong to an application you recognise. A business computer should be reviewed under the office's incident process, especially when shared storage or customer data is involved.

Review recently installed applications

On Windows 11, open Settings, then Apps, then Installed apps. Sort or review the list for software installed around the time symptoms began. Look for an application you remember accepting during another installation, a browser helper you did not intend to add, or a tool that now displays repeated upgrade messages.

Research the publisher through its official site before removing anything unfamiliar. Hardware drivers, accessibility tools and office management software may have names you do not recognise. On a company PC, ask the administrator first. Use the normal uninstall process for unwanted software; do not delete random folders from Windows or Program Files. If uninstalling fails or the application returns, keep that information for support.

Inspect browser settings and extensions

Check the browser's extension page and remove extensions you did not choose or no longer need, using the browser's own controls. Review the home page, default search choice and notification permissions. A site allowed to send notifications can produce alarming popups even when its page is closed. Revoke permission for sites you do not trust.

Test whether the problem affects one browser profile or the whole computer. Avoid importing every extension into a fresh profile before testing, because that may recreate the same issue. Do not reset a work browser without considering saved sessions, managed settings and unsynchronised bookmarks. Make a safe record of what you need, then follow the browser's official reset instructions if necessary.

Distinguish resource use from infection

Press Ctrl+Shift+Esc to open Task Manager. Review CPU, memory and disk use while the problem occurs. A busy process may be an update, a scan or an application handling a large file. Record the process name and publisher information before taking action. Ending an unfamiliar system process can interrupt work or make Windows unstable.

Check available storage in Settings under System, then Storage. Use built-in storage controls to review temporary files instead of downloading an unknown cleaning utility. Review startup applications in Task Manager or Settings and disable only optional apps you understand. If the PC remains slow despite clean scans, consider storage health, cooling, memory or an application fault with a qualified technician.

Treat account compromise separately

Unexpected sign-in alerts, changed recovery details or messages sent without permission need account checks even if a PC scan is clean. From another trusted device, open the service's official site, change the affected password and review active sessions. Use a unique password and enable multi-factor authentication where available. Never share a one-time password with someone offering to fix your account.

Tell an office administrator if a work account or shared file service is involved. Preserve relevant alert times and messages rather than clearing everything. Malware can be one possible cause, but reused passwords, phishing and stolen sessions also need attention. A clean scan cannot establish that an online account is secure.

Decide when to get help

Ask for help when protection will not start, detections return after recommended action, files become inaccessible, or the computer contains sensitive business information. Stop using an affected PC for banking and password changes. Keep backups separate until you know what is being restored, and do not copy suspicious programs to another machine.

For prevention after the checks, read our Windows 11 antivirus guide and ransomware protection advice. Use the official PremiumAV download page for installation files and pricing page for current licence choices. The useful outcome of these checks is a clearer diagnosis and a documented next step, rather than an assumption based on one symptom.

Official references

Windows Security guidance