I like the error trap idea, I didn't think of using something like that. And I haven't checked my error logs yet, but maybe I should.
What I have is a Flash uploader so I can upload multiple files, each file is limited to 1MB in size. Then after the upload is complete Flash calls my PHP script which does some database stuff and creates the thumbnails. The only thing that isn't working is the thumbnail part.
I'm not sure what the problem is because the exact same script works fine on the original domain where I started the project. All of which is on the same server.
I'll check the error logs to see if I can find anything that might help.