PSD download files error

We have a simple form where clients upload their ad and we download it from your server. All of the sudden, we are receiving an "access denied" error message. Please advise.

Thanks

I have cloned and tested your form and first time when I submitted the form and when I tried to open .psd file I got this message. 

However, after further investigation I found out that this happens when a file uploaded actually fails to complete the upload due to some file transfer problems such as intermittent internet connection on the user's end. This causes the file to prematurely complete and thus getting corrupted.

It probably looked like this when user submitted your form and as you can see file is not uploaded yet.

It should look like this.

You can contact your users who made the submissions and request from him the files again.

Hope this will help. Let us know if you need further assistance.