You realize the script in question is Alpha? That means its not ready to be used. Which is an understatement.
Obviously your not a web developer. You would know that when your web browser uploads a file, it tells the web server what type of file it is - and this scripts checks that.
"The non-supported filetype problem results from the file being altered in the process of uploading. That's really all I can tell you. I'm thinking you'll have to ask your webhost about this."
This is bogus. The code in the script specifically checks the data passed by the browser in the MIME headers - not the image data itself. However it is PHP that is pulling the MIME type from the headers, so it could either be a problem with your browser or with PHP.
Having said that, I installed the script myself and it works for me with an JPEG image with Firefox 3 and PHP Version 4.4.8
You neglected to tell us what browser and PHP version you are using or a link to your site to be of much help figuring out why it doesn't work for you.
Edit: It worked using PHP 4.4.8 as mod_php - I switched to PHP 5 CGI, and it fails. This is a problem with PHP 5 then.
Edit: Duh. The script is not written for PHP 5 in mind apparently. PHP 5 does not support $HTTP_POST_FILES - one needs to use $_FILES instead. Problem solved.
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