Can't login as root

[Shin Ogino <shino@inch.com>]

Hi,

After updating a few packages with dselect and rebooting my machine, I
am not able to login as root any more.  When I type root and its
password on login prompt, I do not get any response. I have to use CTR-c
to kill process.

However, I can login as any other users except for root. I tried to run
su and su - from a user, but after typing  password, I did not get
anything.

Does anyone have any idea of what is going on and how to fix this?

Thanks a lot.

Best,
shin ogino