apt-get broken dependency error

[<Michael_Oneppo@brown.edu>]

I recieved the following error while attempting an upgrade:
> apt-get upgrade
Reading Package Lists... Done
Building Dependency Tree... Done
You might want to run `apt-get -f install' to correct these.
Sorry, but the following packages have unmet dependencies:
  xbase-clients: Depends: xlibs (> 4.2.0) but 4.1.0-17 is installed
E: Unmet dependencies. Try using -f.

Following instructions, I got the following error:

> apt-get -f install
Reading Package Lists... Done
Building Dependency Tree... Done
Correcting dependencies... Done
The following extra packages will be installed:
  xlibs 
1 packages upgraded, 0 newly installed, 0 to remove and 218  not upgraded.
8 packages not fully installed or removed.
Need to get 0B/1205kB of archives. After unpacking 262kB will be used.
Do you want to continue? [Y/n] y
(Reading database ... 53328 files and directories currently installed.)
Preparing to replace xlibs 4.1.0-17 (using .../xlibs_4.2.1-4_i386.deb) ...
Warning: /usr/X11R6/lib/X11/xkb symbolic link points to the wrong place.  
Removing.
Unpacking replacement xlibs ...
dpkg: error processing /var/cache/apt/archives/xlibs_4.2.1-4_i386.deb (--unpack):
 trying to overwrite `/usr/X11R6/lib/X11/app-defaults', which is also in package tetex-base
Analyzing /usr/X11R6/lib/X11/app-defaults:
drwxr-xr-x   16 root     root         4096 Jun 21 19:34 /usr
drwxr-xr-x    6 root     root         4096 Nov 28 13:52 /usr/X11R6
drwxr-xr-x    6 root     root         4096 Nov 28 13:54 /usr/X11R6/lib
drwxr-xr-x    9 root     root         4096 Nov 28 13:54 /usr/X11R6/lib/X11
drwxr-xr-x    2 root     root         4096 Nov 28 13:54 /usr/X11R6/lib/X11/app-defaults
ERROR: /usr/X11R6/lib/X11/app-defaults is not a symbolic link.  The package 
preinst script should have failed.
Please report the package name, version, and the text of the above error 
message(s) to <debian-x@lists.debian.org>.
dpkg: error while cleaning up:
 subprocess post-installation script returned error exit status 1
Errors were encountered while processing:
 /var/cache/apt/archives/xlibs_4.2.1-4_i386.deb
E: Sub-process /usr/bin/dpkg returned an error code (1)


The package and version, I assume, is xlibs version 4.2.0 upgrading from 4.1.0-17, as from the first error message.

I tried moving the app-defaults directory as recommended by a colleague and got the same errors.

   Thank you for your time,
         Michael Oneppo