Failed to download repository information

[TenLeftFingers]

Every time I perform a check in the Update Manager, a dialog pops up with "Failed to download repository information". As a result, the "package information" for this system is now 33 days out of date despite a healthy internet connection.

Running: sudo apt-get update
from a terminal shows:

W: Failed to fetch https://private-ppa.launchpad.net/commercial-ppa-uploaders/folder-color/ubuntu/dists/precise/main/binary-i386/Packages The requested URL returned error: 401

W: Failed to fetch https://private-ppa.launchpad.net/commercial-ppa-uploaders/tiberiumalliances/ubuntu/dists/precise/main/binary-i386/Packages The requested URL returned error: 401

E: Some index files failed to download. They have been ignored, or old ones used instead.

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: update-manager 1:0.156.14.11
ProcVersionSignature: Ubuntu 3.2.0-38.61-generic-pae 3.2.37
Uname: Linux 3.2.0-38-generic-pae i686
NonfreeKernelModules: fglrx wl
ApportVersion: 2.0.1-0ubuntu17.1
Architecture: i386
Date: Sat Mar 16 16:53:47 2013
GsettingsChanges:
 com.ubuntu.update-manager first-run false
 com.ubuntu.update-manager launch-time 1363452575
 com.ubuntu.update-manager show-details true
 com.ubuntu.update-manager window-height 776
 com.ubuntu.update-manager window-width 1215
InstallationMedia: Ubuntu 12.04 LTS "Precise Pangolin" - Beta i386 (20120328)
MarkForUpload: True
PackageArchitecture: all
SourcePackage: update-manager
UpgradeStatus: No upgrade log present (probably fresh install)