I contacted support with the problem.
That was the first answer:
we have just received a response from our data center technicians.
We are currently reviewing all details and will get back to you shortly.
Thank you for your time.
2 hours later I got this:
.., the server has a network configuration problem, maybe caused through a false configuration of the firewall.
You can use the server-recovery (KVM) to fix this problem.
That's all I got.
Well, like I said, I just installed ASL on fresh CentOS 6 minimal server using the installer.
Has anyone an idea how I could fix that? I've installed ASL the second time on the server now, each time after reboot the server doesn't come online again...