Well it maybe a perfectly honest glithce in the system, but the fact that the Database error screen had popped up suggests that the database has possibly reached its maximum capacity to effectivly handle the requests its received.
If the database is not maintained for a while it can become a bugger to handle and every now and again falls over. The fact that is has been down all day would suggest the admins have been working hard to recover the data from a backup (just guessing here)
It doubt it was malicious, although it would have been nice to put the forum administration screen up to inform users that the site was being worked on.