The Sasser worm is continuing to cause disruption for large numbers of Windows PC users. The virus can infect PCs running Windows 2000 and XP that are not patched against the loophole it exploits. The first version of the malicious program was discovered on 1 May and since then has spread widely across the internet - read more (http://news.bbc.co.uk/1/hi/technology/3682537.stm)

To check for sasser, to patch your computer and for general advice go to:
http://www.microsoft.com/security/incident/sasser.asp