Microsoft urge users of Internet Explorer to install update
The 'zero-day' bug affects IE 7, 8 and 9 and can be exploited on computers running XP, Vista and Windows 7, enabling others to steal data or take remote control of a computer.
Microsoft has taken the initial step of offering free security software on its website, the Enhanced Mitigation Experience Toolkit, which should be downloaded and installed.
It is quite an advanced piece of software, with settings recognisable to computer technicians, but if you launch it from your list of programs it should offer protection.
Other options are available in an advisory notice from Microsoft, although again it is getting quite technical for regular users.
Until a full update is available from Microsoft it might be best to use an alternative web browser such as Firefox, Chrome or Opera.
The other thing to remember is to be aware that you yourself is the best anti-virus weapon available, don't directly install software attached to emails, be aware of strange messages in email, on Twitter or Facebook and have a questioning mind when online.