This is my upload script. It seems to work with all files even large images I tested it with an image that was 847kb.
hope this helps some
~DE2
$archive_dir = ""; //This is the directory the file will go to
if($_POST['submit'] == 'UPLOAD') {
global $userfile, $userfile_name, $userfile_size,
$userfile_type, $archive_dir, $WINDIR;
if(isset($WINDIR)) $userfile = str_replace("\\","\", $userfile);
$filename = basename($userfile_name);
if($userfile_size <= 0) die ("$filename is empty.");
if(!@copy($userfile, "$archive_dir/$filename"))
die("Can't copy $userfile_name to $filename.");
if(!isset($WINDIR) && !@unlink($userfile))
die ("Can't delete the file $userfile_name.");
}