Strange fopen problem

[radius]

Hi,
I was using latest php5 but as I couldn't find a ffmpeg-php extension for it, I actually swapped to latest php4, and now I'm having a problem when using fopen for urls, when it's used it just stops the script with no error / warning, i tried using the same php.ini used with my php5 too but it changes nothing.
Btw allow_url_fopen is enabled.
Thanks if someone can help.

[phpfreakjav]

<?php
function http_file_exists($url)
{
$f=@fopen($url,"r");
if($f)
{
fclose($f);
return true;
}
return false;
}
?>