"unable to make backup link of" error when running dpkg.

Hi,

I am ruhning into 'unable to make backup link of' inside dpkg hwne i run 'apt-get upgrade'. Can you please tell me how to fix it?

Thank you.

sudo apt-get upgrade
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages will be upgraded:
python-gnome2-extras xfonts-encodings
2 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
Need to get 0B/906kB of archives.
After this operation, 49.2kB disk space will be freed.
Do you want to continue [Y/n]? Y
(Reading database ... 162086 files and directories currently installed.)
Preparing to replace python-gnome2-extras 2.19.1-0ubuntu4 (using .../python-gnome2-extras_2.19.1-0ubuntu7_i386.deb) ...
Unpacking replacement python-gnome2-extras ...
dpkg: error processing /var/cache/apt/archives/python-gnome2-extras_2.19.1-0ubuntu7_i386.deb (--unpack):
unable to make backup link of `./usr/share/doc/python-gnome2-extras/examples/gdl/gdl_combo_button.py' before installing new version: Operation not permitted
Preparing to replace xfonts-encodings 1:1.0.2-1 (using .../xfonts-encodings_1%3a1.0.2-3_all.deb) ...
Unpacking replacement xfonts-encodings ...
dpkg: error processing /var/cache/apt/archives/xfonts-encodings_1%3a1.0.2-3_all.deb (--unpack):
unable to make backup link of `./usr/share/fonts/X11/encodings/large/big5hkscs-0.enc.gz' before installing new version: Operation not permitted
dpkg-deb: subprocess paste killed by signal (Broken pipe)
Errors were encountered while processing:
/var/cache/apt/archives/python-gnome2-extras_2.19.1-0ubuntu7_i386.deb
/var/cache/apt/archives/xfonts-encodings_1%3a1.0.2-3_all.deb
E: Sub-process /usr/bin/dpkg returned an error code (1)