mv /etc/udhcpc/libicd_network_ipv4.script.dpkg-dist /etc/udhcpc/libicd_network_ipv4.script
a blank screen. Not completely black, but almost. Like the screensaver having kicked in, without having made it to final darkness. But it couldn't be woken up.
Why did I do this not entirely necessary upgrade? I had been so happy with my N900, now it seemed gone...
So far, I haven't even seen the sshd to become inaccessible. If that happens only after a rather long time, it would actually be no issue at all for me - I could accept it even as a security enhancement.