Crash Starting : E:_cache->open()failed, please report

Same here. Installed a package last night and after that I could not get into Sysnaptic Package Manager

Honestly, Natty has been the most unstable Unbutu I have ever worked on. My window frames disappear, external monitors go nuts, just now the system rebooted when I opened Firefox. This is a brand new install and I'm getting tons and tons of errors. All appear to have some root in Unity....

Anyways, here is the Synaptic Error:
E: Encountered a section with no Package: header
E: Problem with MergeList /var/lib/apt/lists/ubuntu.mirror.ac.za_ubuntu-archive_dists_natty_main_binary-amd64_Packages
E: The package lists or status file could not be parsed or opened.
E: _cache->open() failed, please report.

Cheers,
JR

Fixed!

I removed all files under /var/lib/apt/lists/

Then did:
sudo apt-get update

After this used graphical Update Manager and Synaptic Package manager without a hitch.

Cheers,
Jacobus

Status changed to 'Confirmed' because the bug affects multiple users.

Got the same problem. Tried to delete old kernel-images (3.2.0.29 and 3.2.0.30), then got the error message:

E: Der dpkg-Prozess wurde unterbrochen; Sie müssen manuell »sudo dpkg --configure -a« ausführen, um das Problem zu beheben.
E: _cache->open() failed, please report.

Restarting Synaptic fails with the same error message. Removing all files in /var/lib/apt/lists/ fails with the following error message:

rm: Entfernen von »lists/de.archive.ubuntu.com_ubuntu_dists_precise_main_i18n_Index“ nicht möglich: Eingabe-/Ausgabefehler

After that, running ls in /var/lib/apt/lists/ stucks and can't be aborted via CMD+C. Running sudo apt-get update gives no output.

After a restart sudo apt-get update and the uninstalling via synaptic worked.

if the status is corrupted, the user needs to clean it first manually