la chiusura del file la farei alla fine...

codice:
$fd = fopen ($listfile, "r");
$contents = fread ($fd, filesize ($listfile));
fclose ($fd);//sposta qui
$entries = explode(",",$contents);
for($i=0;$i<count($entries);$i++)
{
if ($entries[$i] != "")
$choices .= "<OPTION VALUE=\"$entries[$i]\"> ".$entries[$i]."\n";
}
fclose ($fd);
mi sembra...