Description:
------------
When I used session , don't download in Web browser.



Reproduce code:
---------------
<?
//	session_start();  // <= no plobrem
	session_start();  // <= don't download
	
	$file_name = "Download.csv";
	
	$file_ptr = fopen($file_name, "w");	
	
	for( $i = 0; $i < 9; $i++ )
		fwrite( $file_ptr, "$i, ".($i+1).", ".($i+2)."\n" );
	fclose( $file_ptr );
	
	header("Content-Disposition: attachment; filename=$file_name");
	header("Content-type: application/octet-stream");
	
	readfile($file_name);
	
?>