why does download just not happen?

[sfullman]

NOTE: the following code works just fine for files of like a megabyte or even 10 - I'm testing where this fails right now. And it's worked for years:

		$nameAs=preg_replace('/^[a-z0-9]+_/i','',$file);
		header ("Accept-Ranges: bytes");  

		header ("Connection: close");  

		header ("Content-type: application/octet-stream");  

		header ("Content-Length: ". filesize($path));   

		header ("Content-Disposition: attachment; filename=\"$nameAs\"");

	readfile($path);
	exit;

Is there some issue with apache or php.ini file which might be causing a prblem? I am running PHP version 4.4.8

Thanks for your help on this.
Samuel