Our participants (students) are sometimes asked to add an attachment to the post in discussion threads. Lately, several attachments have not been accessible for download. We get either an error or authentication problem message. I can't see a pattern in terms of what type of attachment is uploaded. Sometimes they are JPEGS, or Word or PDFs. This happened yesterday to my co-instructor, but I was able to access the documents and download them.
It's a mystery.
Any help is welcome.