Windows 2000 and Windows NT allows local users to cause a denial of service (reboot) by executing a command at the command prompt and pressing the F7 and enter keys several times while the command is executing, possibly related to an exception handling error in csrss.exe.
http://www.securityfocus.com/bid/3115
http://online.securityfocus.com/archive/1/201151
http://online.securityfocus.com/archive/1/200985