Strange PHP GD lib / Mac problem

[szirtest]

Anyone come across this problem...

I have a form which posts the user specified jpeg file to a PHP script that creates a thumnail from it using the GD library.

This works absolutely fine on my PC with iExplore, but on a Mac (AOL browser - presumably Netscape) the exact same jpeg image causes the PHP script to fail with the following error:

Warning: imagecreatefromjpeg(): gd-jpeg: JPEG library reports unrecoverable
error: in /home/www/clariaup/tools/validatepicture.php on line 11

Warning: imagecreatefromjpeg(): '/home/www/clariaup/dynamic/cut_corner.jpg'
is not a valid JPEG file in /home/www/clariaup/tools/validatepicture.php on
line 11
Problem In opening Source Image

Could this be something to do with the way Macs or Netscape post the multiform data??? I'm using
enctype="multipart/form-data" in the form.

Any help greatly appreciated.