Apt-get: Broken Pipe

["Marcus Deluigi (intern)" <i-mardel@wicresoft.com>]

Hi!

I tried to install an unofficial debian package (AMPortal) by adding a
new ressource to resources.list.
But the installation failed with the error message:

---
apt-get install amportal asterisk-sounds-amportal
[...]
Fetched 2622kB in 1s (2533kB/s)
(Reading database ... 75051 files and directories currently installed.)
Unpacking asterisk-sounds-amportal (from
.../asterisk-sounds-amportal_1.10.009-42_all.deb) ...
dpkg: error processing
/var/cache/apt/archives/asterisk-sounds-amportal_1.10.009-42_all.deb
(--unpac
k):
 trying to overwrite `/usr/share/asterisk/sounds/ext-or-zero.gsm', which
is also in package asterisk
-sounds-extra
dpkg-deb: subprocess paste killed by signal (Broken pipe)
Errors were encountered while processing:
 /var/cache/apt/archives/asterisk-sounds-amportal_1.10.009-42_all.deb
E: Sub-process /usr/bin/dpkg returned an error code (1)
---

and I can't install any other packages anymore, because apt-get reports
unmet dependencies:

---
The following packages have unmet dependencies:
  amportal: Depends: asterisk-sounds-amportal but it is not going to be
installed
  asterisk-config-amportal: Depends: asterisk-sounds-amportal but it is
not going to be installed
E: Unmet dependencies. Try 'apt-get -f install' with no packages (or
specify a solution).
---

How can I restore the initial state (or proceed with the installation)?

btw: I'm running debian sarge, but installed a lot of newer packages
through apt pinning.

Greetings,
Marcus