A common method used by criminals to install malicious programs on your computer is to use a pop-up window that tells you your computer is infected with viruses or spyware, and that you need to buy their program to get rid of these threats. In reality, the only thing wrong with your computer is the pop-up window, and the program that is pretending to be antispyware is actually spyware. An example pop-up is shown below:
If you see something like this, the best thing to do is to press the Alt and F4 buttons on your keyboard together, which will close the active window. Don't click on the "No" button - chances are it isn't a "No" button at all, but a hyperlink that will actually install the rogue program on your computer. You may also see some sort of "warning" window, trying to scare you into believing that your computer is infested with dangerous programs. An example is shown below. It is actually just a webpage, cleverly made to mimic Windows Explorer. If you see something like this, just close the entire window by pressing Alt + F4.
What should I do if a rogue security program manages to install itself on my computer?
If, for whatever reason, the rogue is actually installed on your computer, you will see a window something like this...
... or this:
If this happens, we advise the following. DON'T click on any of the buttons in the program, and DON'T attempt to buy the program. It may be tempting, in order to make the irritating window stop popping up all the time, but you would just be making things worse for yourself. You would be giving your credit card details to people who are known to be criminals, and almost certainly allowing them to install additional software on your computer that could be used to spy on you or allow them to take control of your computer. Furthermore, DON'T do Internet banking or buy anything online while the rogue program is infecting your computer. We strongly advise you to switch the computer off, and call an expert who can remove the infection safely.