Helpdesk Challenge – how can I tell if my PC has a virus?
Computer viruses and malware can cripple a machine at their very worst. But even if your PC hasn’t gone into total meltdown, it’s perfectly possible that a virus is on your system and causing less dramatic disruptions.
The question is, how can you tell if your PC has been infected with a virus or malware?
Read our Which? reviews of the best security software
How to spot a computer virus
First things first, forget everything you’ve ever seen in a Hollywood movie when it comes to computer viruses. Hollywood scriptwriters can write many things, but a convincing approximation of a virus code isn’t one of them.
Viruses do not make a giant skull-and-crossbones appear on your screen. It would be very unlikely for a virus to make your screen suddenly warp and flicker. And they tend not to make your speakers turn on and laugh at you.
The actual signs to look out for are more mundane, but can be just as frustrating.
A slow-running computer
Top of the list of things to look out for is a PC that’s running more slowly than usual. If you’re finding that your system is grinding to a halt, it’s possible that a virus has infected your PC.
Make sure your anti-virus software is up to date and run a full-scan immediately.
Read our top tips on keeping your PC running smoothly
Frequent program or system crashes
If you’re finding that your computer is regularly crashing, or that programs are freezing frequently, a virus could be to blame.
Try using the Windows Reliability Monitor to see a history of your computer’s performance. This ought to give you a better impression of how often it’s been misbehaving, and if there’s been a significant increase in crashes recently. This could tip you off on a virus infecting your system at a certain point.
Read our guide on how to use the Windows 7 Reliability Monitor
Problems accessing files and folders
If you’re struggling to open files which normally present no problems, or if your folder structures seem to have changed, it may mean that a virus has infected your computer.
As a virus spreads and corrupts files on your system, it’s not unusual to find that these files are difficult to access. Sometimes even opening a folder can cause your system to hang or crash.
The best defence is a reliable suite of security software. Kept up-to-date, security software can typically fend off the worst threats from the web.
Have you ever experienced a computer virus on your system? What were the symptoms you noticed, and how did you deal with the problem? Share your experiences in the comments below.
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David Pollock
What are the risks of having a virus if one is running (in my case) an automatically updated Norton 360 anti-virus program?
Rich Parris
Hi David – if you keep your security software up to date, and treat emails from unknown sources with due caution, you’re likely to stay safe. However, malware and other nasties can occasionally slip through the net – make sure your software is set to perform regular system scans, and if you’re ever in doubt, you can prompt a new scan yourself
Ian Savell
A lot of the most pernicious viruses turn off your Antivirus software and block access to popular AV web sites, so if you see those symptoms you are probably infected. One way they do that is to hijack your computer’s DNS lookup – the system that tells your computer where to find websites you want to visit – and so you might also experience a lot of mis-directions where you enter a website name and get something else or nothing at all.
Unfortunately Antivirus software, however much you pay for it, can’t detect all viruses and can’t clean all viruses. So it is very important to use your PC in a way that avoids infection. No anti-virus can be 100% effective, so prevent rather than cure.
A lot of viruses use known weaknesses in older versions of software to infect you, so you should keep everything up to date. The best way I know of to do that is first to accept all Window updates as son as they arrive and second to download and use the free program “Secunia PSI” to keep the rest of your software in line. Regular updating can be a bit of a pain but a lot easier than undoing an infection!
Martyn Faller
In my opinion the single best way to reduce the chance of becoming infected (nothing is 100% guaranteed) is to use an account where you are a standard user and not an administrator, that way even if your AV fails to detect the malware the ability to alter system files is limited.
Peter Allen
Is a I Mac any less susceptible to infection?
Gosport Cat
My laptop is autoscanned and protected by McAfee and I never open a dodgy email. Yet my system is slower than any computer I’ve used in the last 20 years. Yesterday it took over 30 mins to download 74 emails (nothing big and no attachments). Loading Word or other standard apps takes ages. And then Firefox, or Word, or Outlook etc will stop ‘responding’ and another wait ensues until it either begins working again or the program crashes. The “Windows is now looking for a solution” pop-up is obviously ironic. And since moving house (same B/band supplier) my laptop refuses to connect to the internet securely – any attempt to force a secure connection is automatically replaced with yet another insecure one. Yet McAfee & Windows updates are current and scans find nothing. What more can I do? I can see me launching my laptop at the wall in frustration if it doesn’t speed up, stop crashing and allow secure internet access. Arrrrgggggh!
Jason
Hi Gosport Cat, I personally don’t like McAfee, I use AVG for free and find it equally as good and free! Try a program called Advanced System Care 6 and do a scan, you’ll have the option to repair any issues found. Then have a look in “Toolbox” and run a start up manager scan, it could be that programs are starting when you turn your PC on and slowing the system down, turn off anything not needed i.e. Adobe speedlauncher, Google toolbar notifier etc which aren’t really needed. The software is free (although does have a pay version). A scan once a week seems to keep my laptop running smoothly.