update-rc.d: error

[hf42]

Software
XBian version: 1.0.RC2
XBMC version: 13.0.RC1
Overclock settings: default

Hardware
Cubox-i2-ultra
Network: wireless
Connected devices: TV, usb storage, cubox-i2 internal devices

Problem description:
update / upgrade after an "apt-get -f install" breaks with:

Code:

plymouth (0.8.8-16) wird eingerichtet ...
update-initramfs: deferring update (trigger activated)
update-rc.d: error: expected NN after start
usage: update-rc.d [-n] [-f] <basename> remove
       update-rc.d [-n] <basename> defaults [NN | SS KK]
       update-rc.d [-n] <basename> start|stop NN runlvl [runlvl] [...] .
       update-rc.d [-n] <basename> disable|enable [S|2|3|4|5]
        -n: not really
        -f: force

The disable|enable API is not stable and might change in the future.
dpkg: Fehler beim Bearbeiten des Paketes plymouth (--configure):
Unterprozess installiertes post-installation-Skript gab den Fehlerwert 1 zurück
Fehler traten auf beim Bearbeiten von:
plymouth
E: Sub-process /usr/bin/dpkg returned an error code (1)

I've googled a while and found that may be an issue in an
var/lib/dpkg/info/*.postinst - script. but I didn't find the right one (I checked the plymouth and the initramfs, but my knowledge about this scripts is less than basic)

How to reproduce:
1. I started with a sd-card copy (with dd) from 14. April: Nearly clean image, actual update/upgrade, some small changes: wifi-config + lirc-config
2. apt-get update: no error
3. apt-get upgrade: some issues, -f was recommended by script
4. apt-get -f install: more installations
5. apt-get update: no error
6. apt-get upgrade: breaks with the code above

Are there any recommendations?
Thanks