Not every slow computer has a virus, and not every virus makes your computer slow. But there are some telltale signs that something malicious is going on behind the scenes. Here are five red flags to watch for — and what to do if you spot them.
1. Your Computer Is Suddenly Much Slower
Yes, computers slow down over time. But if your machine went from running fine to crawling overnight — especially when you're not running anything heavy — that's suspicious. Malware often runs processes in the background that eat up your CPU and memory. You might notice your fan spinning constantly or simple tasks like opening a browser taking forever.
To check, open Task Manager (Ctrl + Shift + Esc on Windows) and look at the Processes tab. If something you don't recognize is using a huge chunk of CPU or memory, that's worth investigating.
2. Pop-Ups and Strange Ads Everywhere
If you're seeing pop-up ads on your desktop, in your system tray, or ads injected into websites that normally don't have them, you've likely picked up adware. This is one of the most common types of malware — it's not always destructive, but it's annoying and it means something got installed on your system without your real consent.
Be especially wary of pop-ups that tell you your computer is infected and offer to "fix" it. That's almost always a scam trying to get you to install more malware or pay for fake software.
3. Programs Opening or Closing on Their Own
If applications are launching without you opening them, your browser keeps redirecting to sites you didn't visit, or programs crash for no reason, something may be controlling your system. Some malware operates by hijacking your browser to send you to ad-revenue sites. More dangerous variants can give an attacker remote access to your machine entirely.
If your mouse is moving on its own or windows are opening while you're watching, disconnect from the internet immediately and seek help. That's a sign someone may have active remote access.
4. Your Antivirus Is Disabled
One of the first things sophisticated malware does is try to disable your antivirus software. If you notice that Windows Defender or your third-party antivirus has been turned off and you didn't do it, that's a major warning sign. Some malware will also block you from visiting antivirus websites or downloading removal tools.
If you can't turn your antivirus back on or it keeps getting disabled, your system is likely compromised and needs professional attention.
5. Friends Are Getting Strange Messages from You
If people in your contacts are receiving emails or messages you didn't send — especially ones with links or attachments — your email account or computer may be compromised. Malware can hijack your email client to spread itself to your contacts, or an attacker may have gained access to your account credentials.
Change your email password immediately (from a different, clean device if possible), enable two-factor authentication, and scan your computer for malware.
What to Do If You Think You're Infected
First, don't panic. Most malware infections are fixable. Here are the immediate steps to take: disconnect from the internet to prevent the malware from communicating with its server or spreading further, then run a full scan with your antivirus. If your antivirus is disabled or you don't have one, try downloading Malwarebytes Free from another computer and transferring it via USB drive.
If the infection is serious — your antivirus can't remove it, your system is unusable, or you suspect someone has remote access — it's time to bring it to a professional. Trying to fix a deep infection yourself can sometimes make things worse, especially if ransomware is involved.
Think your computer might be infected? Bring it to FlexTech and we'll run a thorough diagnostic. We'll remove the malware, make sure your system is clean, and help you set up protection to prevent it from happening again.