More Information on Viruses and Trojans 

What is a virus? All viruses are pieces of software that insert themselves into program files, make copies of themselves in other program files so when the program is run and cause damage to your files. They take many forms, some may lay dormant until a certain date before striking.  Others will change to dialing code on your internet connection resulting in you having a hefty phone bill. There is one virus which just mischievously turns the display on your monitor upside down.

How do viruses get into  my computer?  Most viruses will try and enter your computer via the internet connection.  Instead  you could inadvertently  introduce them by using a CD, memory stick or floppy disc with an infected file copied from a friends computer.

What is a Trojan?  A Trojan is a program which is inserted into your PC to allow hackers to remotely access your PC and read your confidential files containing such things as passwords. It also uses your PC to gain access to other PCs and web sites. A firewall will monitor traffic in and out of your computer and prevent such attacks  

How can I protect my computer? By having a firewall and  a virus checker installed.  The virus checker must be kept up to date. A virus checker will prevent a virus from entering the computer and put a warning on the screen, thus preventing any damage being done. A virus checker can be installed after a virus has infected a computer and although it will be able to remove the virus it may not be able to undo the damage the virus has done

Norton Internet Security 2011 or 2012 and Norton 360 are  packages from Symantec which offer  complete Internet security including virus protection and a firewall to prevent unauthorised access to your PC.  A 3 licence copy retails for around £25- £40. Although recommended by Which? I do not recommend free virus checkers.  

Most routers include a firewall which is better than the firewall on your computer whether it is provided as part of the Windows Package or your Internet Security suite. This is because it is contained in equipment separate from your PC and so less likely to attack.  This assumes that your router is protected with a strong password and any wireless has strong key to protect it. 

Remember Prevention is Better than Cure!