Network interface randomly does not come up with IP

[DJC]

I have configured eth0 in /etc/network/interfaces to get a static IP:

auto lo
iface lo inet loopback

auto eth0
iface eth0 inet static
        address 192.168.0.23
        netmask 255.255.255.0
        network 192.168.0.0
        broadcast 192.168.0.255
        gateway 192.168.0.1
        # dns-* options are implemented by the resolvconf package, if installed
        dns-nameservers xxx.yyy.zzz.www
        dns-search xxxxxx.eu

When the Raspi boots up, sometimes it prints something like "My IP is 192.168.0.23" and sometimes it does not. The interface is always up, but depending on whether or not this message has been print, an IP address has been assigned or not.

Manually executing ifdown eth0 and ifup eth0 always brings up the interface with the IP assigned.

During boot there always is a messsage like "Sorry, there is already an instance of ifplugd for eth0 running". This message also appears if the IP is assigned.

# ifplugd -v
ifplugd 0.28 (SVN: 124)

Running kernel 3.12.22+ #691

C library Version: 2.13-38+rpi2+deb7u1

Funnily enough, I have three raspis, only one shows this behavior. The only changes that have been made to the system are
- hostname changed
- usernames changed
- /var, /home, /tmp, /run moved to an usb disk
- installed some java application (ccuhistorian) which regularly polls data from an external home automation system.