Steps to re-produce the bug:

1. Pick any page to edit.
2. In the rich text editor, type something.
3. Switch to the Wiki markup editor.
4. Your text is gone.

If this doesn't happen, try it three times. You may try to switching editors before the the draft is saved.

I discovered this bug on the following page.
http://confluence.atlassian.com/display/csi/Automated+Test+Environment