Столкнулся с проблемой вызова сабжевой функции в Windows 7 x64. При увеличении размера пакета запроса до 250 и выше байт возвращает ошибку 998 — неверная работа с памятью. Полез в МСДН онлайновый — там следующее: 
  
 
Код:
RequestOptions [in]
  
A pointer to the IP header options for the request, in the form of an IP_OPTION_INFORMATION structure. On a 64-bit platform, this parameter is in the form for an IP_OPTION_INFORMATION32 structure.
  
This parameter may be NULL if no IP header options need to be specified.
  
ReplyBuffer [in, out]
  
A buffer to hold any replies to the echo request. Upon return, the buffer contains an array of ICMP_ECHO_REPLY structures followed by the options and data for the replies. The buffer should be large enough to hold at least one ICMP_ECHO_REPLY structure plus RequestSize bytes of data.
  
On a 64-bit platform, upon return the buffer contains an array of ICMP_ECHO_REPLY32 structures followed by the options and data for the replies.
ReplySize [in]
  
The allocated size, in bytes, of the reply buffer. The buffer should be large enough to hold at least one ICMP_ECHO_REPLY structure plus RequestSize bytes of data. On a 64-bit platform, The buffer should be large enough to hold at least one ICMP_ECHO_REPLY32 structure plus RequestSize bytes of data.
		
		Код:
RequestOptions [in]
A pointer to the IP header options for the request, in the form of an IP_OPTION_INFORMATION structure. On a 64-bit platform, this parameter is in the form for an IP_OPTION_INFORMATION32 structure.
This parameter may be NULL if no IP header options need to be specified.
ReplyBuffer [in, out]
A buffer to hold any replies to the echo request. Upon return, the buffer contains an array of ICMP_ECHO_REPLY structures followed by the options and data for the replies. The buffer should be large enough to hold at least one ICMP_ECHO_REPLY structure plus RequestSize bytes of data.
On a 64-bit platform, upon return the buffer contains an array of ICMP_ECHO_REPLY32 structures followed by the options and data for the replies.
ReplySize [in]
The allocated size, in bytes, of the reply buffer. The buffer should be large enough to hold at least one ICMP_ECHO_REPLY structure plus RequestSize bytes of data. On a 64-bit platform, The buffer should be large enough to hold at least one ICMP_ECHO_REPLY32 structure plus RequestSize bytes of data.

 Не там искал. А насколько я понял, что для POINTER_64 аналога в pascal пока нет. Embarcadero еще пока только анонсирует Delphi x64.
 Не там искал. А насколько я понял, что для POINTER_64 аналога в pascal пока нет. Embarcadero еще пока только анонсирует Delphi x64.