> just like this.
> int httrack_wrapper_postprocesshtml(char** html,int*
> len,char* url_adresse,char* url_fichier) {
>   char *p = _strdup(*html);
>   *html = p;
> }

Humm, can't reproduce the issue witht the 3.41 code, using the callback:

static int postprocess(httrackp *opt, char** html,int* len,const char*
url_address,const char* url_file) {
  char *old = *html;
  *html = strdup(*html);
  free(old);
  return 1;
}

Can you provide the stackframe of the process please ?
By the way, are you running on Linux ?