INT 21 - LANtastic v4.1+ - TERMINATE USER
        AX = 5FCBh
        ES:DI -> ASCIZ server name in form "\\machine"
        DS:SI -> blank-padded username.  A null char = wildcard.
        DS:DX -> blank-padded machine name.  A null char = wildcard.
        CX = minutes until termination (0 = immediate)
Return: CF clear if successful
        CF set on error
            AX = error code
Note:   you must have the "S" privilege to use this call
        you cannot log yourself out using this call