I've been using beta 2 for my new blog at http://www.fpaulwilsonproject.com and everything's been fine. This evening I logged in and the control panel suddenly says I have 0 Posts, 0 Categories, etc, etc. It even says I have no users despite allowing me to log in and correctly identifying me in the "Howdy" line. Meanwhile the blog itself looks and acts fine.
I've never seen anything like this, but figured it was a glitch so I went ahead and upgraded (manually) to beta 3. When I returned to my admin area it said I needed to upgrade the database ,which I did. Then it returned to the same admin panel devoid of data. I checked the database and it's fine.