Could not initialize the package information

Did you try:
sudo dpkg --configure -a

Please check if your sources.list is 'clean'.
http://wiki.ubuntuusers.de/sources.list
http://wiki.ubuntuusers.de/apt-get

Hi Sam,

- I tried sudo dpkg --configure -a with no positive result. The error remains.
- The sources.list should be clean:
  deb http://de.archive.ubuntu.com/ubuntu/ jaunty main restricted
  deb http://de.archive.ubuntu.com/ubuntu/ jaunty-updates main restricted
  deb http://de.archive.ubuntu.com/ubuntu/ jaunty universe
  deb http://de.archive.ubuntu.com/ubuntu/ jaunty-updates universe
  deb http://de.archive.ubuntu.com/ubuntu/ jaunty multiverse
  deb http://archive.canonical.com/ubuntu jaunty partner
  deb-src http://archive.canonical.com/ubuntu jaunty partner
  deb http://security.ubuntu.com/ubuntu jaunty-security main restricted
  deb http://security.ubuntu.com/ubuntu jaunty-security universe
  deb http://security.ubuntu.com/ubuntu jaunty-security multiverse
  deb http://download.virtualbox.org/virtualbox/debian jaunty non-free
- I also checked the above mentioned links. But I still have no idea.

Regards
Thomas

Ok,
this will remove the lists, repair and update:

sudo rm -rf /var/lib/apt/lists/*
sudo dpkg --configure -a
sudo apt-get update
sudo apt-get upgrade
sudo apt-get -f install

##If this error occurs (usually the lists should be created automatically):
E:Lists directory /var/lib/apt/lists/partial is missing"

you need to create the lists manually:
sudo mkdir -p /var/lib/apt/lists/partial

Cleanup:
sudo apt-get autoremove && sudo apt-get clean && sudo apt-get autoclean

This problem is normal , have you signed the Virtual Box you have added lately by a GPG key. I see you didn't so go back to the tutorial where you have read how to add the VirtualBox and download the GPG key. If you don't remember where I'll give the easiest solution for that.

1- Remove The current Virtual Box from the software source list. when closing that window , click on reload on the shown message.

2- Download ubuntu tweak from here.
http://ubuntu-tweak.googlecode.com/files/ubuntu-tweak_0.4.7.1-1%7Ejaunty1_all.deb

Double clock on the downloaded deb file. and click then on Install This package. It may download some files.

3- Open it from Applications->System Tools-> ubuntu tweak.
Click in that window on Applications then Third Party Ressource and click Unlock , Type your password. And then From that list check Virtual Box and click refresh .

Now You haven't lost anything , and you have corrected the problem ; Now you can make the update safely without any error.

The lesson you must get from this problem ; is that any software source you add must identify it by a GPG key , otherwise the system will consider it as unsafe. and you find always the gpg key in the website where you are reading how to add the key.

Good luck