Is Ubuntu 12.04.1 windows wubi installer broken?

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http://askubuntu.com – I installed the newest release of Ubuntu 12.04 with the wubi installer. The computer is up and running with Ubuntu, I am typing this in Firefox and I can use all the software that was supplied with the installation. However, it seems there is only a small selection of new apps that I am able to install. I have not done anything else on this installation except 1) run wubi to get Ubuntu in there and 2) start it up and 3) try to install these applications that just won't install. For example, I managed to install Inkscape and gParted. However, I could not install the latest proprietary nVidia d (HowTos)