The "Downadup" worm is continuing to cause disruption for large numbers of Windows PC users. The first version of the malicious program is reported to have infected more than 9 million computers around the world by taking advantage of a vulnerability in Microsoft Windows, which has been exposed since October 2008.
While most home users allow Windows to automatically download updates to protect
itself, many business and government users such as the Ministry of Defence and
a number of hospitals in the UK have been affected.

Once your computer is infected, as well as attempting to infect other computers on the same network, it tries to download yet more malicious software from the internet. This, in turn, allows remote access to, and total control of, the infected
computer by shadowy criminal types from who-knows¬where.
To get rid of it, you have to go to Windows Update, and get hold of some strong anti¬virus software.