update-manager fails due to wrong sources

[Satchit Bhogle]

Update Manager fails to download any updates. It asks to check the internet connection, but my internet connection is fine. I have tried this with a connection requiring proxy and two separate connections without proxy. UM throws up an error message pasted below. In addition, my notification areas has an indicator which says:
"The update information is outdated. This may be caused by notification problems or by a repository that is no longer available. Please update manually by clicking on this icon and then selecting 'Check for Updates' and check if some of the listed repositories fail."

satchit@awesomeness:~$ lsb_release -rd && apt-cache policy update-manager
Description: Ubuntu 11.10
Release: 11.10
update-manager:
  Installed: 1:0.152.25.8
  Candidate: 1:0.152.25.8
  Version table:
 *** 1:0.152.25.8 0
        500 http://in.archive.ubuntu.com/ubuntu/ oneiric-updates/main i386 Packages
        500 http://security.ubuntu.com/ubuntu/ oneiric-security/main i386 Packages
        100 /var/lib/dpkg/status
     1:0.152.25 0
        500 http://in.archive.ubuntu.com/ubuntu/ oneiric/main i386 Packages

Error output:
W:GPG error: http://ppa.launchpad.net oneiric Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY F192197F81992645, W:GPG error: http://ppa.launchpad.net oneiric Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 326DDB7DA68563AE, W:GPG error: http://ppa.launchpad.net oneiric Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY C2518248EEA14886, W:Failed to fetch http://security.ubuntu.com/ubuntu/dists/oneiric-security/Release Unable to find expected entry 'independent/source/Sources' in Release file (Wrong sources.list entry or malformed file)
, W:Failed to fetch http://in.archive.ubuntu.com/ubuntu/dists/oneiric/Release Unable to find expected entry 'independent/source/Sources' in Release file (Wrong sources.list entry or malformed file)
, W:Failed to fetch http://in.archive.ubuntu.com/ubuntu/dists/oneiric-updates/Release Unable to find expected entry 'independent/source/Sources' in Release file (Wrong sources.list entry or malformed file)
, W:Failed to fetch http://in.archive.ubuntu.com/ubuntu/dists/oneiric-backports/Release Unable to find expected entry 'independent/source/Sources' in Release file (Wrong sources.list entry or malformed file)
, E:Some index files failed to download. They have been ignored, or old ones used instead.

ProblemType: Bug
DistroRelease: Ubuntu 11.10
Package: update-manager 1:0.152.25.8
ProcVersionSignature: Ubuntu 3.0.0-16.28-generic 3.0.17
Uname: Linux 3.0.0-16-generic i686
ApportVersion: 1.23-0ubuntu4
Architecture: i386
CheckboxSubmission: 6a389bf83db22bee5a58087f9e3fc863
CheckboxSystem: 2954e74ba17fb0e37fc942cd1d9fab4e
Date: Fri Mar 9 16:23:21 2012
InstallationMedia: Ubuntu 11.10 "Oneiric Ocelot" - Release i386 (20111012)
PackageArchitecture: all
SourcePackage: update-manager
UpgradeStatus: No upgrade log present (probably fresh install)