imagepng dont display both in ff and ie

[shotokan99]

i have this issue:

showpic.php
================================================
$ch = curl_init();
$timeout = 0;
curl_setopt ($ch, CURLOPT_URL, $xmyurl);
curl_setopt ($ch, CURLOPT_CONNECTTIMEOUT, $timeout);
// Getting binary data
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_BINARYTRANSFER, 1);

$image = curl_exec($ch);
curl_close($ch);

header('Content-type: image/png');
$xim=@imagecreatefromstring($image);

$xbase = @imagecreatetruecolor(130,168);
$xback=imagecolorallocate($xbase, 255,255,255); //green
imagefill($xbase,0,0,$xback);

$xhead=@imagecreatefrompng('xhead.png');
imagecopy($xbase,$xhead,10,0,0,0,108,28);
imagecopy($xbase,$xim,0, 28, 0, 0, 130,140);
imagepng($xbase);
================================================

then i have this code to display the pic:

echo'
<font color="#FF0000" size="4">Congratulations!!!</font><br>
<span style="font-weight: 400"><font size="2">
<font color="#000000">Here is your pic ;-)</
font><br>
</font></span>
<img src="showpic.php?xurl='.$newurl.'">
';

the issue is, on my machine both on ie and ff the image display
perfectly.
however on some machines it doesnt display the entire pic just the
$xhead value.
what is wrong with it? can some pls tell me how to fix this problem?