Error 303 when trying to upload files

When I try to upload files through sermon speaker I get an error 303. This occurs when uploading sermon notes or audio files.

Are you seeing this in frontend or backend or both? Do you have the Flash uploader enabled?
What PHP version are you using?

I guess the error is coming from the swfupload library SermonSpeaker uses for the uploader.

The error occurs on the backend.

We're using php 5.2

I don't really have a clue why this happens. Also Google doesn't bring any good results if I search for swfupload and error 303.
Maybe you can try to disable all non-core system plugins to see if any of those is messing with the uploader. Other than that I can't help you much unfortunately.

What I know is that SermonSpeaker itself doesn't generate this message, and it's working on my testing sites. So it has to be related to your server or your computer/windows/browser and swfupload (or the S3 library if you use AmazonS3).