Hacked: all my registered users account have vanished
 

I initially had problems with my brand new phpBB3 forum as someone had managed to get into ACP and started modifying my posts and decided to upgrade to vBulletin thinking that the security levels would help keep out intruders.

However* yesterday evening I had 80 registered members and I woke up this morning and that list had whittled down to 13 registered members plus someone had removed my Register link so no one could register. Plus* the registered members who had posted content have had their accounts deleted.

This is so frustrating. I have an inkling of who the person doing this is (my old vBulletin forum expert who is probably upset that I am creating a new forum to rival his poor forum). Just wondering what options I have to stop this happening again. No one else has access to my username/password and no one has access to my cpanel account.

I'm just wondering if there are any additional security settings I can install or if I've missed something. I installed vBulletin 3.8.2 so I believe this is the latest version.

Any ideas?