Otro problema de actualización

Buenos días,
Hoy, salió el Administrador de Actualizaciones para descargar e instalar 6 actualizaciones.
Una de ellas no se pudo instalar y en detalles dice lo siguiente:

"installArchives() failed: E: Firma del archivo invlida
E: Prior errors apply to /var/cache/apt/archives/firefox_15.0.1+build1-0ubuntu0.12.04.1_i386.deb
debconf: fallo al ejecutar apt-extracttemplates: Desplazamiento ilegal
Preconfigurando paquetes ...
E: Firma del archivo invlida
E: Prior errors apply to /var/cache/apt/archives/firefox_15.0.1+build1-0ubuntu0.12.04.1_i386.deb
debconf: fallo al ejecutar apt-extracttemplates: Desplazamiento ilegal
Preconfigurando paquetes ...
E: Firma del archivo invlida
E: Prior errors apply to /var/cache/apt/archives/firefox_15.0.1+build1-0ubuntu0.12.04.1_i386.deb
debconf: fallo al ejecutar apt-extracttemplates: Desplazamiento ilegal
Preconfigurando paquetes ...
E: Firma del archivo invlida
E: Prior errors apply to /var/cache/apt/archives/firefox_15.0.1+build1-0ubuntu0.12.04.1_i386.deb
debconf: fallo al ejecutar apt-extracttemplates: Desplazamiento ilegal
Preconfigurando paquetes ...
(Reading database ...
(Reading database ... 5%%
(Reading database ... 10%%
(Reading database ... 15%%
(Reading database ... 20%%
(Reading database ... 25%%
(Reading database ... 30%%
(Reading database ... 35%%
(Reading database ... 40%%
(Reading database ... 45%%
(Reading database ... 50%%
(Reading database ... 55%%
(Reading database ... 60%%
(Reading database ... 65%%
(Reading database ... 70%%
(Reading database ... 75%%
(Reading database ... 80%%
(Reading database ... 85%%
(Reading database ... 90%%
(Reading database ... 95%%
(Reading database ... 100%%
(Reading database ... 356767 files and directories currently installed.)
Preparing to replace libdbus-1-3 1.4.18-1ubuntu1.1 (using .../libdbus-1-3_1.4.18-1ubuntu1.3_i386.deb) ...
Unpacking replacement libdbus-1-3 ...
Preparing to replace ntfs-3g 1:2012.1.15AR.1-1ubuntu1 (using .../ntfs-3g_1%%3a2012.1.15AR.1-1ubuntu1.2_i386.deb) ...
Unpacking replacement ntfs-3g ...
Preparing to replace libxslt1.1 1.1.26-8ubuntu1.1 (using .../libxslt1.1_1.1.26-8ubuntu1.2_i386.deb) ...
Unpacking replacement libxslt1.1 ...
Preparing to replace dbus 1.4.18-1ubuntu1.1 (using .../dbus_1.4.18-1ubuntu1.3_i386.deb) ...
Unpacking replacement dbus ...
Preparing to replace dbus-x11 1.4.18-1ubuntu1.1 (using .../dbus-x11_1.4.18-1ubuntu1.3_i386.deb) ...
Unpacking replacement dbus-x11 ...
dpkg-deb: error: `/var/cache/apt/archives/firefox_15.0.1+build1-0ubuntu0.12.04.1_i386.deb' is not a debian format archive
dpkg: error processing /var/cache/apt/archives/firefox_15.0.1+build1-0ubuntu0.12.04.1_i386.deb (--unpack):
 subprocess dpkg-deb --control returned error exit status 2
Processing triggers for initramfs-tools ...
No apport report written because MaxReports is reached already
update-initramfs: Generating /boot/initrd.img-3.2.0-31-generic-pae
Processing triggers for man-db ...
Processing triggers for ureadahead ...
ureadahead will be reprofiled on next reboot
Errors were encountered while processing:
 /var/cache/apt/archives/firefox_15.0.1+build1-0ubuntu0.12.04.1_i386.deb
Error in function:
Setting up libdbus-1-3 (1.4.18-1ubuntu1.3) ...
Setting up libxslt1.1 (1.1.26-8ubuntu1.2) ...
Setting up ntfs-3g (1:2012.1.15AR.1-1ubuntu1.2) ...
update-initramfs: deferring update (trigger activated)
Setting up dbus (1.4.18-1ubuntu1.3) ...
Setting up dbus-x11 (1.4.18-1ubuntu1.3) ...
Processing triggers for libc-bin ...
ldconfig deferred processing now taking place
Processing triggers for initramfs-tools ...
update-initramfs: Generating /boot/initrd.img-3.2.0-31-generic-pae"

saludos