D-Link kindly remind of there will be virus outbreak in April fools' day, a worm Conficker, also known as Downup, Downadup and Kido, which was surfaced in Oc. 2008, this computer worm can infect your computer and spread itself to other computers across a network automatically, without human interaction. The worm exploits a previously patched vulnerability MS08-065 in the Windows Operation System, e.g. Windows 2000, Windows XP, Windows Vista, Windows Server 2003,Windows Server 2008, Windows 7 Beta, and Windows Server 2008 R2 Beta.

For securing your network, please make sure that your NetDefend UTM firewall has downloaded the latest Anti-Virus signatures which can protect your network from the zero-day attack of this vulnerability.

Reference:
http://en.wikipedia.org/wiki/Conficker
http://www.microsoft.com/protect/computer/viruses/worms/conficker.mspx