Different kernels behave differently--touchpad not working, files in /dev missing

["Masatran (Rajasekaran Deepak)" <masatran@research.iiit.ac.in>]

I am using Debian "Testing". A few days ago, I did a dist-upgrade and also
installed a new kernel:
Old kernel: 2.6.5-1-386
New kernel: 2.6.12-1-k7
There are two problems:

OLD KERNEL:
X11 is not starting now. Something wrong with the touchpad.
    $ ls -l /dev/psaux
    crw-rw-rw-  1 root root 10, 1 2004-05-21  /dev/psaux
    $ cat /dev/psaux
    cat: /dev/psaux: No such device
    # cat /dev/psaux
    cat: /dev/psaux: No such device
All /dev files are present in the old kernel.

NEW KERNEL:
Many of the files in /dev are missing.
    $ aumix
    aumix:  error opening mixer
    $ ls /dev/mixer
    ls: /dev/mixer: No such file or directory
    $ dpkg -l udev
    ii  udev           0.074-2        /dev/ and hotplug management daemon
X11 and the touchpad are fine in the new kernel.
-- 
Masatran (Rajasekaran Deepak) <http://research.iiit.ac.in/~masatran/>