Erro ao fazer upload de arquivo xls

[mestre fyoda]

Mensagem de Warning

Warning:  move_uploaded_file(upload/RETORNO_VS_NEW_02_06.xls) [function.move-uploaded-file]: failed to open stream: No such file or directory in C:\Inetpub\wwwroot\importar\upload.php on line 5

Warning:  move_uploaded_file() [function.move-uploaded-file]: Unable to move 'C:\WINDOWS\Temp\php1C4.tmp' to 'upload/RETORNO_VS_NEW_02_06.xls' in C:\Inetpub\wwwroot\importar\upload.php on line 5
Possível ataque! Informações:
Array
(
    [file] => Array
        (
            [name] => RETORNO_VS_NEW_02_06.xls
            [type] => application/vnd.ms-excel
            [tmp_name] => C:\WINDOWS\Temp\php1C4.tmp
            [error] => 0
            [size] => 2015232
        )

)

<form action="upload.php" method="post"
enctype="multipart/form-data">
<label for="file">Filename:</label>
<input type="file" name="file" id="file" /> 
<br />
<input type="submit" name="submit" value="Submit" />
</form>

</body>
</html>

<?
$uploaddir = 'upload/';
$uploadfile = $uploaddir. $_FILES['file']['name'];
print "<pre>";
if (move_uploaded_file($_FILES['file']['tmp_name'], $uploaddir . $_FILES['file']['name'])) {
echo "Upload OK";
} else {
print "Possível ataque! Informações:\n";
print_r($_FILES);
}
print "</pre>";
?>

[cassianooliver]

ou o seu diretório não existe, ou o caminho tá errado....