Comment 8 for bug 1304878

concerning post #1:
for removing single packages without dependencies use
sudo dpkg -r --force-depends libopenblas-base
sudo dpkg -r --force-depends libopenblas-dev
This worked for me on 12.04LTS for reenabling multicore calculation.
Nevertheless the now missing dependencies will be reinstalled with apt-get update.
To avoid this see http://askubuntu.com/questions/17745/how-to-remove-a-deb-without-removing-its-dependencies