I have to say I'm extremely impressed with your reply. It's too bad for me today because one of my small forum had been hacked.
Restore backup means lost members/post xxx hours. I think after upgrade my forum to version 3.0, I forgot change CHMOD file config.php ( it's 777 ). Someone got it & drop table member in mysql database.
If recover from recent database backup, I think our members have to request the new password too ?