Stahovani souboru pres hlavicky , kesovani a problem

/**
 * trida pro stazeni souboru
 * tato trida umoznuje stejnou funkcnost jak v IE tak ve firefoxu
 * 
 * @author Dostal Ales
 * @version 1.1
 * @date 13.4.2006
 *
 */
 
class DownloadFile
{

/****************************** METODY TRIDY ******************************/

    /**
     * konstruktor tridy pro stazeni souboru
     * 
     * @param    String        $file        zdroj k souboru, ktery se bude stahovat
     * 
     */
    function ExecuteDL($file)
    {
        // zjisteni, zda soubor existuje
        if (!is_file($file)) { 
            die("<b>404 Soubor neexistuje!</b>"); 
        }
    
        // ziskani informaci o souboru
        $len = filesize($file);
        $filename = basename($file);
        $file_extension = strtolower(substr(strrchr($filename,"."),1));
    
        // nastaveni content-type pro vybrane soubory
        switch( $file_extension ) 
        {
            case "pdf": $ctype="application/pdf"; break;
            case "exe": $ctype="application/octet-stream"; break;
            case "zip": $ctype="application/zip"; break;
            case "doc": $ctype="application/msword"; break;
            case "xls": $ctype="application/vnd.ms-excel"; break;
            case "ppt": $ctype="application/vnd.ms-powerpoint"; break;
            case "gif": $ctype="image/gif"; break;
            case "png": $ctype="image/png"; break;
            case "jpeg":
            case "jpg": $ctype="image/jpg"; break;
            case "mp3": $ctype="audio/mpeg"; break;
            case "wav": $ctype="audio/x-wav"; break;
            case "mpeg":
            case "mpg":
            case "mpe": $ctype="video/mpeg"; break;
            case "mov": $ctype="video/quicktime"; break;
            case "avi": $ctype="video/x-msvideo"; break;
    
            # tyto soubory nemohou byt stazeny
            case "php":
            case "htm":
            case "html":
            case "txt": die("<b>Není možné stahovat ". $file_extension ." soubory!</b>"); 
            break;
    
            default: $ctype="application/force-download";
        }
    
        # odeslani hlavicek
        session_cache_limiter("private"); # v IE nelze stáhnout dokument pres HTTPS
        header("Pragma: public");
        header("Expires: 0");
        header("Cache-Control: must-revalidate, post-check=0, pre-check=0");
        header("Cache-Control: public");
        header("Content-Description: File Transfer");
      
        # generuje typ pro content-type
        header("Content-Type: $ctype");
    
        # co stahuji
        $header="Content-Disposition: attachment; filename=".$filename.";";
        header($header );
        header("Content-Transfer-Encoding: binary");
        header("Content-Length: ".$len);
        readfile($file);
        exit;
        
    } # public function __construct($file)
    
} # class APIDownloadFile

php_flag zlib.output_compression on
php_value zlib.output_compression_level 8