This happened on a hosting company I had an account with..
It was in EV1.
The company kept getting DDOS attacks against the server I was on, EV1 simply unplugs any server receiving DDOS attacks meaning all customers on that server are down.
Everytime the server came up, about 10 minutes later, it was taken down.
This must have happened for at least 3 days until the host moved all clients to a new server.
I really don't like the way EV1 deals with DDOS, they don't try help the host, I have seen a lot of hosts complaining about the same thing.
I don't know if they are meant to, or even if they have changed now but I didn't think it was very helpful.
unplugging a server doesn't do anything to help, the attack will continue when it is up again anyway