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Slow, frozen or infected computer? How to tell what's really wrong

By Matthew DeRicco, Glen Cove. Updated October 2026.

A slow, frozen or misbehaving computer can have many causes, and a virus is only one of them. Guessing wrong costs time and money. Here's how I sort out what is going on, what you can safely check yourself, and when it makes more sense to replace the machine.

Why is my computer slow? It has many possible causes

Too many programs starting at boot, a nearly full drive, stuck Windows updates, or an older hard drive that can't keep up can all make a computer crawl. Virus and malware removal helps when malware is present, but it won't fix a failing drive or a machine with too little memory. After checking the system, the fix might be a cleanup, an update, a drive or memory upgrade, or a conversation about replacing the computer.

Pop-ups, warnings and scams

Fake security warnings, browser redirects, unknown programs and messages demanding payment are designed to feel like emergencies. Do not call a number shown in a pop-up, do not give remote access to someone who contacts you, and do not type passwords into a page you did not open yourself.

A real cleanup goes beyond deleting one program. I check for unwanted software, risky browser extensions and changed settings. If you entered passwords after a suspected scam, change them from a device you trust. Nobody can promise that nothing was exposed, but a careful process lowers the chance of it happening again.

A computer that won't start

"Won't start" can mean no power at all, a black screen, a stuck logo, a blue screen, or Windows restarting in a loop. Each one points somewhere different. If the drive is still readable, I move your files first. If you hear clicking, or files suddenly disappear, stop restarting the computer, because that can make a weak drive worse. Data recovery may still be possible, depending on what failed.

Email, printers and new computers

Not every call is a broken computer. Many are email that stopped syncing, a printer that dropped off the Wi-Fi, or files that need to move from an old machine to a new one. A careful setup means nothing important gets left behind on the old computer.

Repair or replace?

I ask four questions. Can the problem be fixed reliably? Will the fix solve the problem you notice every day? How much useful life will it add? And what would a comparable replacement cost?

A well-kept computer a few years old is often worth repairing, especially when a drive or memory upgrade fixes the slowness. An old, inexpensive laptop with several problems may not be. I'll tell you honestly when replacing it is the better choice, even when that means no repair job for me. You can see the full list of what I handle on the computer repair page.

Get ready for a visit

• Write down the exact message you see and when it appears.
• Keep the charger handy, along with any logins and recovery keys you're comfortable sharing.
• Decide what matters most: family photos, work email, speed, or setting up a replacement.

I come to you, I explain why I need access to your device, and I treat your files and accounts with care. Estimates are free, and I tell you what I find and what it would cost before I do any repair.

Avoid the next problem

Keep important files in more than one place, such as an external drive and a trusted cloud backup, and check now and then that you can actually open them. Keep Windows, your browser and your security software updated, use unique passwords, and turn on multi-factor authentication where you can. If something feels off, stop and ask before you click.