Warum funktioniert das Script manchmal und manchmal nicht?

#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <stdlib.h>
#include <winsock.h>
#include <io.h>

#define HTTP_PORT 80

int main(int argc, char **argv)
{
 int sock;
 struct sockaddr_in host_addr;
 struct hostent *hostinfo;
 char *host, *file;
 char command[1024];
 char buf[32768];
 int bytes_sent, bytes_recv;

 /* Ist der Aufruf korrekt? */
 if (argc != 3) {
 fprintf (stderr, "Aufruf: httprecv host file\n");
 exit (EXIT_FAILURE);
 }

 host = argv[1];
 file = argv[2];

 /* ggf. Winsock initialisieren */
 #ifdef _WIN32
 WSADATA wsaData;
 if (WSAStartup (MAKEWORD(1, 1), &wsaData) != 0) {
 fprintf (stderr, "WSAStartup(): Kann Winsock nicht initialisieren.\n");
 exit (EXIT_FAILURE);
 }
 #endif

 /* Socket erzeugen */
 sock = socket (AF_INET, SOCK_STREAM, 0);
 if (sock == -1) {
 perror ("socket()");
 exit (EXIT_FAILURE);
 }

 /* Adresse des Servers festlegen */
 memset( &host_addr, 0, sizeof (host_addr));
 host_addr.sin_family = AF_INET;
 host_addr.sin_port = htons (HTTP_PORT);

 host_addr.sin_addr.s_addr = inet_addr (host);
 if (host_addr.sin_addr.s_addr == INADDR_NONE) {
 /* Server wurde nicht mit IP sondern mit dem Namen angegeben */
 hostinfo = gethostbyname (host);
 if (hostinfo == NULL) {
 perror ("gethostbyname()");
 exit (EXIT_FAILURE);
 }
 memcpy((char*) &host_addr.sin_addr.s_addr, hostinfo->h_addr, hostinfo->h_length);
 }

 /* Verbindung aufbauen */
 if (connect(sock, (struct sockaddr *) &host_addr, sizeof(struct sockaddr)) == -1) {
 perror ("connect()");
 exit (EXIT_FAILURE);
 }

 /* HTTP-GET-Befehl erzeugen */
 sprintf (command, "GET %s HTTP/1.0\nHost: %s\n\n", file, host);

 /* Befehl senden */
 bytes_sent = send (sock, command, strlen (command), 0);
 if (bytes_sent == -1) {
 perror ("send()");
 exit (EXIT_FAILURE);
 }

 // Antwort des Servers empfangen und ausgeben */
 while ((bytes_recv = recv (sock, buf, sizeof(buf), 0)) > 0) {
 write (1, buf, bytes_recv);
 }
 if (bytes_recv == -1) {
 perror ("recv()");
 exit (EXIT_FAILURE);
 }

 printf ("\n");

 closesocket(sock);
 WSACleanup();
 
 return 0;
}