After a few days offline, the blog is back. It happened that there was a scheduled shutdown in the web farm, and when the computer got back up the VmWare server (with Linux host) with the virtual machine hosting the blog started misbehaving. After some tribulation, I decided to install VmWare on my Windows server, and move the existing vm on it. However, the configuration of the software running the blog had a hardcoded IP address, so by changing the machine IP, I had to reconfigure it (easy once I found out).
Anyway, everything should be back up as normal, although the URL now refers to a different IP, that of the new server. Sorry for the issue and let me hope the new solution will be a bit more stable.