Booting ubuntu hangs in usb.rc

[Le grand pinguin]

Hello list,

i have successfully updated my Debian/testing to Ubuntu following
the instructions on http://wiki.ubuntulinux.org/WartyWarthog_2fUpgradeNotes
The system boots fine and works when i use my standard Debian 2.6.7-powerpc
kernel image (but see [1]) but fails to boot when i use the 2.6.8.1-3-powerpc
kernel that gets installed by running "apt-get install linux-powerpc".
According to the boot messages the systems hangs in 'usb.rc'.
Besides keyboard and mouse (logitech - on separate usb interfaces) no
USB devices are attached. The usb subsystem seems to work prior to
that since the console responds to keyboard input.
Any help?

 TIA Ralf Mattes