Index key broken, possible causes sources.list
 

I need help installing programs again because I am trying to install a win32 codec to play wmv files. I am completely new to linux and I guess I'm fucking up my system because now I can't install anything. Here is the error messages I receive when I try to download Banshee

This is a major failure of your software management system. Please check for broken packages with synaptic, check the file permissions and correctness of the file '/etc/apt/sources.list' and reload the software information with: 'sudo apt-get update' and 'sudo apt-get install -f'.

The sudo apt-get update and sudo apt-get install -f have errors when I enter them as follows
jeff@jeff-System-Product-Name:/etc/apt$ sudo apt-get install -f
Reading package lists... Done
Building dependency tree
Reading state information... Done
Correcting dependencies... Done
The following package was automatically installed and is no longer required:
linux-headers-2.6.35-22
Use 'apt-get autoremove' to remove them.
The following extra packages will be installed:
vlc-data
The following NEW packages will be installed:
vlc-data
0 upgraded, 1 newly installed, 0 to remove and 286 not upgraded.
6 not fully installed or removed.
Need to get 0B/7,781kB of archives.
After this operation, 22.8MB of additional disk space will be used.
Do you want to continue [Y/n]? y
(Reading database ... 136188 files and directories currently installed.)
Unpacking vlc-data (from .../vlc-data_1.1.4-1ubuntu1.4_all.deb) ...
dpkg-deb (subprocess): data: internal gzip read error: '<fd:0>: data error'
dpkg-deb: subprocess <decompress> returned error exit status 2
dpkg: error processing /var/cache/apt/archives/vlc-data_1.1.4-1ubuntu1.4_all.deb (--unpack):
subprocess dpkg-deb --fsys-tarfile returned error exit status 2
Processing triggers for hicolor-icon-theme ...
Errors were encountered while processing:
/var/cache/apt/archives/vlc-data_1.1.4-1ubuntu1.4_all.deb
E: Sub-process /usr/bin/dpkg returned an error code (1)

sudo apt-get update
Fetched 837B in 6s (121B/s)
Reading package lists... Done
W: GPG error: http://archive.getdeb.net maverick-getdeb Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY A8A515F046D7E7CF

Please someone help!!

Maybe there is some problem with the cache stored in the /var/cache/apt directory. See if deleting it and making a apt-get update solves the problem. Don't forget to backup the deleted directory in case anything happens.