by Sabine Helmke.
We're using Moodle 2.3.1+ and we have similar reports from students, too. It happens with docx and pptx, windows7 notebook or macbook. Only difference: When they use a desctop computer with the same assignment and file, it works.
I even don't know where to look?!
German version: "Dateityp ... wird nicht akzeptiert"