class.upload.php is a powerful and mature PHP class to manage uploaded files, and manipulate images in many ways. The script is available under a GPL license.
I was running 0.19 on a PHP4 installation. When switching to PHP 5.2.4, it no longer worked and I got above error message. Upgrading class.upload.php to 0.25 solved the issue.
Try to raise your local memory to 20M, 32M or more.
You can add this in your script:
Or in a .htaccess file:
Cheers
Raz