IT problem...website/server hacking

Can anyone help with ideas please...

One of the sites I am staffing has been experiencing problems.

We took over and merged with another site a fortnight ago. Some of the members from that site rebelled and started a new breakaway site and certain disruptive members were banned from ours.

One of the breakaway members posted the full details of servers and other personal details of the owner of our site. This same individual is an IT specialist. He is banned from our site.

Is it possible for a virus or other such sabotage to be done against our servers by this individual?

Over the last few days our servers have gone down around 15 mins after banned members have tried to enter the site.

The site is currently down again now, shortly beforehand it was not submitting posts properly or increasing post count and general freezing.

Any ideas...can someone actually stuff up another site's servers like this...especially when that person has complete server details etc?

Thanks for that.

The techies have now rolled back the site to before the banned member tried to re-enter his modify options tab on his user cp.

So far, so good, all banned members are now IP banned rather than just account disabled and although about half a dozen posts were lost by rolling back, everything seems to be OK now.

We have made a formal complaint to the hosting company of the breakaway site. Not sure how much good that it will do, but we can but try.

The thing that gets me the most about all this is that we tried to be reasonable with these people, a mix of Brits and US, but it has ended up with almost the entire lot being banned. Their previous site's owner did not tell them that he had sold the site to us and they were not happy and seeing as they could not target their anger at him, they chose to do so at us instead.

Cest la vie I spose.