Dear angels…
On July 7th server.my-web-host.org got compromised by an unknown person who hacked an ftp account and could upload a php shell script.
On July 10th, ( probably the same person ) used this script to install a malicious cron job on the server with target to run a DOS attack against another server. For this reason the server got disconnected on July 10 (yesterday) at 10:00 am from the network for a complete check.
The server got reconnected at 09.00 pm July 10 and all services are running fine again.