Teaching staff are occasionally being unenrolled from one of our Moodle courses, spontaneously. It's happened to three people so far. One is a "teacher" and two are "non-editing teachers".

One (teacher) sent an email that he lost access at 12:20am after he replied to forum post. When checked at 8:00am, he was enrolled.

Teaching staff are manually put into courses. Students are uploaded and enrolled by CSV file upload through the "upload users" tool. Students are removed using the flat-file enrollment plugin. No teaching staff are uploaded, enrolled or deleted via any automated means.

The staff can be re-enrolled into the courses easily enough, but the un-enrollment ghost can visit the same person more than once.