Building Dependency Tree... Done
You might want to run 'apt-get -f install' to correct these:
The following packages have unmet dependencies:
  libc6-dev: Depends: libc6 (= 2.3.6-15) but 2.3.2.ds1-22 is to be installed
  libfontconfig1-dev: Depends: libfontconfig1 (= 2.2.3-4) but 2.3.1-2 is to be installed
  locales: Depends: glibc-2.3.5-3
  mozilla-firefox: Depends: firefox (= 1.5.dfsg+1.5.0.4-1) but it is not going to be installed
E: Unmet dependencies. Try 'apt-get -f install' with no packages (or specify a solution).
debian:~#

debian:~# apt-get -f install
Reading Package Lists... Done
Building Dependency Tree... Done
Correcting dependencies... Done
The following extra packages will be installed:
  fontconfig fontconfig-config libc6 libfontconfig1 libfontconfig1-dev
  libfreetype6 libfreetype6-dev
Suggested packages:
  glibc-doc
The following packages will be REMOVED:
  base-config
The following NEW packages will be installed:
  fontconfig-config
The following packages will be upgraded:
  fontconfig libc6 libfontconfig1 libfontconfig1-dev libfreetype6
  libfreetype6-dev
6 upgraded, 1 newly installed, 1 to remove and 755 not upgraded.
3 not fully installed or removed.
Need to get 0B/6183kB of archives.
After unpacking 6459kB disk space will be freed.
Do you want to continue? [Y/n]

(Reading database ... 79796 files and directories currently installed.)
Preparing to replace libc6 2.3.2.ds1-22 (using .../libc6_2.3.6-15_i386.deb) ...

Name Service Switch update in the C Library: pre-installation question.

Running services and programs that are using NSS need to be restarted,
otherwise they might not be able to do lookup or authentication any more.
The installation process is able to restart some services (such as ssh or
telnetd), but other programs cannot be restarted automatically.  One such
program that needs manual stopping and restart after the glibc upgrade by
yourself is xdm - because automatic restart might disconnect your active
X11 sessions.

Known packages that need to be stopped before the glibc upgrade are:
        xdm kdm gdm postgresql xscreensaver

This script detected the following installed services which must be
stopped before the upgrade:
        gdm

If you want to interrupt the upgrade now and continue later, please
answer No to the question below.

Do you want to upgrade glibc now? [Y/n] Y  (no gives same error)

WARNING: Your kernel version indicates a revision number
of 255 or greater. Glibc has a number of built in
assumptions that this revision number is less than 255.
If you've built your own kernel, please make sure that any
custom version numbers are appended to the upstream
kernel number with a dash or some other delimiter.
dpkg: error processing /var/cache/apt/archives/libc6_2.3.6-15_i386.deb (--unpack):
 subprocess pre-installation script returned error exit status 1
Errors were encountered while processing:
 /var/cache/apt/archives/libc6_2.3.6-15_i386.deb
E: Sub-process /usr/bin/dpkg returned an error code (1)