And the same thing happens in Firefox, not just IE!
What happened in my case was that students had a < sign in what they were writing (code). This got interpreted as "malformed HTML" and just disappeared. When I put in a page break between questions, it works fine, each has their own editor. But both questions were linked, I needed them to be able to review what they had done on the previous exercise.
I assume that most people have one question per page - I normally do, and I've been using Moodle for final exams for at least 3 years now. Just happened to make sense this time.
In a quiz, nothing should ever be parsed away!
Oh, and I need a "Text is code" button that works better than just "preformatted" HTML, which puts in extra line feeds that are extremely annoying!
The editor needs more work, and should not delete stuff unasked!