source: http://www.securityfocus.com/bid/12889/info

Microsoft Windows XP is prone to a remote denial of service vulnerability. This issue can allow a remote unauthorized user to shutdown an affected computer.

A remote attacker uses the TSShutdn.exe command to restart or shutdown a computer.

It should be noted that the exploitation of this vulnerability may require the attacker to be part of the same domain. This BID will be updated when more information is available.

Microsoft Windows XP Service Pack 1 is affected by this issue. 

Tsshutdn 0 /SERVER:yyyzzz /DELAY:0