infected

How do I know if my computer has been infected with a virus?

If your anti-virus programme is working properly and its virus definitions are fully up to date, you will get a warning window, informing you of the existence of the virus and prompting you to take action. However, if you aren't so lucky, here is a list of things that should cause you to suspect that you have been infected:

• Be extremely cautious when opening email attachments. It is best to avoid opening any attachment received from an unknown source. If you need to do so, you should first save the attachment to a folder on your computer, then open the appropriate application (such as Microsoft Word or Adobe Acrobat) yourself. If you use the programme's File menu to open the attachment manually, rather than double-clicking the file or allowing your email programme to open it automatically, you are less likely to contract a virus.

If you use a computer, the sad fact is that you need to know about computer viruses. There are many different ways to classify viruses, each with its own set of colourfully named categories. Worms, macroviruses, trojans and backdoors are some of the more well-known examples. Many of these viruses spread over the internet using email, malicious webpages or other means to infect unprotected computers.

Why does my computer slow down sometimes?

The most likely reason is that there are too many applications and programmes running at the same time. Usually closing down a few applications will speed things up. You may have unseen programmes, such as anti-virus software, running in the background. Check your system tray (in Windows, this is in the lower left-hand corner) to see if you have any programmes running in the background. A slow computer may also be infected with a computer virus.

Why does my computer screen go off while I'm working?