We recently set up a new virtual machine running Windows Server 2008 and slapped a copy of SQL server 2005 on it. The server had running and in use without a hitch for about two weeks. The only real maintenance we've done on it is to move the partition the database files resided (done nearly a week ago) and we ran the Database Engine Tuning Advisor to look at some suggestions for new indices yesterday around 12PM.
Just after 5PM while the software was being used as usual someone notified me that the program no longer seemed to work properly. I checked the database and not only was data specific to his use of the program was gone, but every table of fifty tables or so seemed to be wiped of all records.
After talking to the application developers in extensive length, it became clear that this wasn't a remotely possible capability of their software.
In the scramble to get back from our feet we cloned a backup of the VM over the running copy between restarting and it's been running five for about a day ever since. Consequently, we've no logs of the events leading up to the problem itself.
Have you seen anything like this happen before? (All records in all tables of a database just... gone.) Does anyone have a reasonable theory as to how this could occur and what if anything would be a reasonable measure of prevention?