The same thing happened to me... read below:
I'm hosting phpbb 2.0 on Windows 2000 Advance Server with all security patches updated. Running mysql 3.23.47-nt and php 4.2. Since May 6th all forums, messages and users have been deleted. Whenever I load the back up, it gets deleted too. I changed the database username and password and for almost 18 hours no forums or users were deleted. Then on today May 7th everything was deleted again. I've checked my server for any viruses and reinstalled phpbb 2.0. No success with preventing the board from being deleted. I checked my IIS logs and I don't see any hack attempts. Could this be a problem in the script... by the way I have pruning turned off. And I'm running my server on a stand alone system.
my board: http://myscene.urbanrave.com
It always post this message when the board gets deleted: This is an example post in your phpBB 2 installation. You may delete this post, this topic and even this forum if you like since everything seems to be working!
Any help would be appreciated.