<?php
function hash_part($fp,$start,$length) {
	$ctx = hash_init('md5');

	$remaining=$length;
	$chunkSize=65536;
	while ($remaining > 0) {
		$read = hash_update_stream($ctx, $fp, $chunkSize);
		if($read != $chunkSize) {
			echo "Unexpected read value $read, when we had $remaining bytes left\n";
			echo "We ".(feof($fp)?'ARE':'are NOT')." in EOF\n";
		}
		$remaining -= $read;
		//printf("\r%04.1f%%",(1-$remaining/$length)*100);
	}
	//echo "\n";
	return hash_final($ctx);
}
$fp = fopen('sl-x86-3.4.loop1-to-3.4.loop2b.xd3','rb');
$hash = hash_part($fp,0,40*1024*1024);
echo "$hash\n";
if ($hash != "40d99ed59fba1844207283d25f833c35") {
	echo "WHAT THE HELL IS GOING ON\n";
}
fclose($fp);
?>

This time I was lucky; failed on first try:

>for /L %i in (1,1,10) do @php recover.php
40d99ed59fba1844207283d25f833c35
fb03339de843c8e421fc885e01a53ca3
WHAT THE HELL IS GOING ON
40d99ed59fba1844207283d25f833c35
40d99ed59fba1844207283d25f833c35
40d99ed59fba1844207283d25f833c35
40d99ed59fba1844207283d25f833c35
40d99ed59fba1844207283d25f833c35
40d99ed59fba1844207283d25f833c35
40d99ed59fba1844207283d25f833c35
40d99ed59fba1844207283d25f833c35

But no strange $read.