Disable the POSIX and OS/2 Subsystem.

Windows 2000 and XP come with little-documented subsystems it at allow compatibility with UNIX and OS/2 systems These rues systems are enabled by default but so rarely used that they are best off bring disabled completely to prevent possible service hijackings.

To disable these subsystems, open the registry and navigate to HKEY LOCAL MACHINESYSTEMCurrentControlSetControlSession ManagerSubSystems. Delete the subkeys Os2 and Posix. then reboot.