Top 10 Symptoms That Your PC May Be Infected

How do you know if your computer has a virus, a worm, a trojan horse infection, spyware, malware, crimeware or any of the other known types of infection? Obviously, everyone's PC is different, so it is up to each person to keep an eye on the known and documented causes.

Although not all of the following symptoms will necessarily indicate your PC has an infection, if you note more than just one of them happening at the same time, there is a high probability and you would be advised to look into it further.

1. Performance is sluggish now compared to what it was when the computer was new. Unfortunately, there is no single cause; it is likely to be any of the following or a combination of them: virus, worm, spyware, Adware, rootkit (provides remote access to a PC without the user's knowledge).

2. PC taking longer to boot up. This happens anyway as you load more and more programs, especially if your computer is older and you're trying to run the latest resource hungry applications, but it's worth checking for malware or other infection that has been added to the start-up sequence.

3. Unexpected shutdowns and restarts. This can be very frustrating if you are doing original work, especially if auto-save is turned off or infrequent. A virus is the most likely cause of this problem.

4. Your PC freezes up and you can't do anything; the mouse won't move and may be showing the hourglass or equivalent symbol, but it is frozen and even Windows Task Manager won't open. This may be a hardware problem, such as faulty RAM, but can be caused by an infection.

5. Wrong web page opens. When you type a URL or click on a link, you are taken to a completely different site, possibly one where you receive an offer to buy through an affiliate link (someone trying to get you to buy a product that they receive a commission for the sale) or worse, you are taken to an adult or porn site. If this happens, there's a big chance that spyware is at work here.

6. Your Homepage or browser settings are changed. This can be from some software you have installed (it is considered unethical installation practice to do this) but it can also be a sign that you have spyware lurking. Spyware at its best is software that puts your eyes in front of an offer to buy a product that your browsing history shows you have an interest in.

7. Pop-ups appear when you're surfing the net. These can be when you've looked at an offer to buy something, decide not and go to close the page. This isn't an infection; it's known as an OTO - a one time offer to buy a lesser product at a lower price, for example. A pop-up may also be a form of revenue-raising by the website owner, who gets paid for every time they show a product offer for someone else. However, if a pop-up appears when you're not loading a closing or loading a page, it could also be an infection.

8. Pop-up Alerts Saying You Have An Infection. DON'T click on these; the chances are it is a trojan horse that will spread a virus or attempt to steal personal information from your PC.

9. Toolbars appear and you didn't install them. These are often installed along with some software you wanted on your system, and unless you are wide-awake during installation and un-tick them, they are loaded in the default installation. Equally, though, malicious toolbars can be installed by malware, so check it out and see.

10. Emails that you didn't send or posts you didn't make. Isn't it embarrassing when a friend tells you that you sent them a strange message or an email with a virus? There are worms and viruses that will go through your address book and send a copy of itself to all your contacts! Or, if your friends tell you that you've made a post on their wall of a social media site and you didn't make it, do a check for malware.

There are also other obvious signs such as money going missing from your bank account, high phone bills or iTunes usage, for example. It pays to check your balance or usage frequently.

To prevent, and treat if necessary, any of the above make sure you protect your computer and yourself. You can use your operating system's built-in security software if it is good enough, install a standalone security suite or use a combination of programs which together will protect your system and allow you trouble-free computing.