Diagnostic keyboard works, Power Manager keyboard doesn't


I have a Rev B4 Beagleboard. Following the instructions at
http://code.google.com/p/beagleboard/wiki/BeagleboardRevCValidation, I
can plug a keyboard into a powered USB hub, and a mini-B connector
from the hub into the OTG slot (pins 4 and 5 were shorted today), and
the keyboard works like a champ. Additionally, the lights above each
of the 4 USB slots of the hub (not just the one with the keyboard
plugged in) all light up.

When I use the latest power management kernel image from
the keyboard doesn't work. Additionally, the lights above the USB
slots on the hub light up briefly, but then go dark.

Does the keyboard not work because the power management kernel is
saving power by having them off or something? My Linux experience is
limited to using Unix periodically (and briefly) at various jobs, plus
Unix in college (as an example of how long ago that was, I heavily
used Athena widgets in various projects).

Any suggestions would be welcome.

As a (hopefully unrelated) aside, periodically it seems like various
directories of my root filesystem disappear. This is especially a
problem with the /dev directory, since then I get the "Unable to open
an initial console. Kernel panic - not syncing: No init found. Try
passing init= option to kernel." It doesn't surprise me I get this
message, since /dev/console, /dev/tty#, and more are all gone.
Possible explanations for that?

Thanks very much,
Bill Bock