Let’s say that you are casually surfing the web, when suddenly a window pops up and asks you to use a program that you don’t recognize to scan your computer for viruses. STOP! It could be a fake virus scan. Although there are numerous free virus scanning programs out there that actually work, there are also a lot of programs that will try to trick you into downloading bad software, or that will try to get you to buy something that you don’t need. If you are suspicious about running a free virus scan, take the following steps to ensure that your computer remains virus free:

FIRST ASK YOURSELF: Do I already have a working anti-virus program?
If you already have anti-virus software, and there is a different program that you haven’t heard of trying to scan your computer, then you should probably close the program and run the anti-virus software that you already own.

ANOTHER QUESTION: Did you request for your computer to be scanned?
Usually legitimate anti-virus programs will not continuously ask you if you want your computer to be scanned. If the program is constantly pestering you to allow it to scan your files, or if it is automatically opening itself repeatedly, then you may want to get rid of the annoying program and try a free program like Spybot Search and Destroy, which only scans your computer when you request a scan.

DON’T BE TRICKED:
Many malicious virus scans tend to tell you that your computer is horribly infected with viruses in order to scare you into buying their program. In reality, purchasing their software may only stop their program from annoying you, and if the software is no good, it could end up leaving your PC open to other viruses.

One especially malicious program, called Anti-virus 2009, installs itself on your computer and tells you that your computer is horribly infected with numerous viruses. The program tells you that if you pay a hefty sum of money, the viruses will be deleted for you. In reality, Anti-virus 2009/2010/2011 is a malicious program, and it can be removed using several free programs, including Malwarebytes’ Anti-Malware.

Is the virus scan running inside of a web browser?

Most real free virus scans are not run inside a browser window. If you are running Internet Explorer, Firefox, or any other web browser, and a free virus scan is running in the browser window, you can probably close that program without hurting anything. If you are having trouble closing your browser while running a free virus scan, you can hit alt+F4 to force the window to close. Or, if you are using tabs, you can hit ctrl+tab to switch to a different tab and finish saving things before you close the browser.

One exception is Trend Micro’s House Call, a legitimate free virus scan program that runs inside of your web browser.

Get free virus protection from well known and trusted sources. It is important research every free anti-virus program, and to find reviews on other websites before you try installing one. Here are a few decent programs that I have used:

If all else fails, then pay for Antivirus Software.

If you have tried some or all of the free methods, but still feel the need to pay for software, then you may want to try Trend-Micro, McAffee, BitDefender or any of the other anti-virus programs on the market.
Tips & Warnings

Please Note: It is not advisable to install too many anti-virus programs on your computer at once, because they can sometimes cause one another to run improperly. Personally, I keep a maximum of two anti-virus programs on my computer.
Please proceed with caution, and if you don’t know anything about computers, get someone smarter to do it for you.