When I upgraded to 12.04 all the 32bit libraries was removed. When I used Synaptic to upgrade, Synaptic installed all the 32bit libraries. When I later used apt-get to install a ppa, I was told to use autoremove to remove all the 32bit libraries, which I did.
After this Synaptic wanted to install the libraries again, but now I marked ia32-libs forinstead. The installation works fine, but I am not able to install Skype as Skype depeneds on ia32-libs.
When I try to install ia32-libs, I get this error printout
ia32-libs: Depends: ia32-libs-multiarch
Have you tried installing ia32-libs-multiarch ? If you get any more dependency issues, install those as well.
I had the same problem. This worked for me:
It's likely that those packages are missing on the mirror that you are using.
You could consider switching to a different mirror which hopefully has a more up to date package list.