Signs My Computer Has a Virus
This isn't one symptom but a pattern — a combination of unusual behaviour that doesn't have an obvious explanation like a recent update or new program you installed intentionally.
Quick answer: The clearest signs are unexpected pop-ups, a browser that's changed on its own, programs you don't remember installing, a computer that's suddenly much slower, or antivirus software that's been disabled without your input. Any single sign is worth checking; several together are worth acting on.
Likely causes
- Pop-ups, redirects or unwanted new browser toolbars
- The computer running much slower than normal, particularly if it came on suddenly
- Programs opening or closing on their own, or ones you don't remember installing
- Antivirus or Windows Security showing as disabled without you turning it off
- Friends or contacts receiving messages from you that you didn't send
What you can safely check yourself
- Check Settings > Apps for anything unfamiliar installed recently
- Confirm Windows Security (or your antivirus) is actually enabled and up to date
- Run a full scan with Windows Security as a first, free step
When it needs a proper look
If a scan finds something, or several of these signs are present together, a proper clean-up is worth doing rather than continuing to use the computer normally in the meantime.