cforms II

Our client is having issues with their form. I have tested and each test I sent has come through fine. They have also been able to upload files from their office computer. Their computer at home and all of their clients have not been able to successfully upload files through the form. They normally receive 5-10 requests a day and all week have received none. I have checked server-side issues and everything is fine. Their clients have been successfully using the upload form on their previous website, so their shouldn’t be firewall issues either. Any other ideas?