Newbie - upgrade question

[Zerkani_user_list <zerkani_user_list@snet.net>]

Need help!

When I ran the security upgrade,  I get the following error  message. How do I 
resolve this error?.

localhost:/home/zerkani# apt-get upgrade
Reading Package Lists... Done
Building Dependency Tree... Done
1 packages upgraded, 0 newly installed, 0 to remove and 0  not upgraded.
21 packages not fully installed or removed.
Need to get 0B/3422kB of archives. After unpacking 4096B will be used.
Do you want to continue? [Y/n] y
debconf: unable to initialize frontend: Gnome
debconf: (Unable to load Gnome -- is libgnome-perl installed?)
debconf: falling back to frontend: Dialog
(Reading database ... 27513 files and directories currently installed.)
Preparing to replace xlibmesa3 4.1.0-16 (using 
.../xlibmesa3_4.1.0-16woody1_i386.deb) ...
Unpacking replacement xlibmesa3 ...
dpkg: error processing 
/var/cache/apt/archives/xlibmesa3_4.1.0-16woody1_i386.deb (--unpack):
 trying to overwrite `/usr/X11R6/lib/libGLU.so.1.3', which is also in package 
xlibmesa3-glu
dpkg-deb: subprocess paste killed by signal (Broken pipe)
debconf: unable to initialize frontend: Gnome
debconf: (Unable to load Gnome -- is libgnome-perl installed?)
debconf: falling back to frontend: Dialog
debconf: unable to initialize frontend: Gnome
debconf: (Unable to load Gnome -- is libgnome-perl installed?)
debconf: falling back to frontend: Dialog
Errors were encountered while processing:
 /var/cache/apt/archives/xlibmesa3_4.1.0-16woody1_i386.deb
E: Sub-process /usr/bin/dpkg returned an error code (1)
localhost:/home/zerkani#

Thanks,

Zerkani