Ubuntu fails to install cuda toolkit

Question

I want to install cuda toolkit on ubuntu 14.04, so I downloaded cuda-repo.deb from nVidia site and then ran:

sudo dpkg -i cuda-repo-ubuntu1404_6.5-14_amd64.deb

But it fails. There are no error messages, it just freezes up and that's all. I cancelled the installation with Ctrl + C.

Afterwards when I try to install something with apt-get, I get this message:

E: dpkg was interrupted, you must manually run 'sudo dpkg --configure -a' to correct the problem.

When I try to execute the command sudo dpkg --configure -a, I get

Setting up cuda-repo-ubuntu1404 (6.5-14) ...

and then it freezes. Can I fix this problem? Delete this package or something.
UPDATE
i fix my problem, mb it will help to someone: this deb package try to add repo-key, so in postinst there is a string

wget -q -O - http://developer.download.nvidia.com/compute/cuda/repos/GPGKEY | apt-key add - || echo "Failed to add GPGKEY at http://developer.download.nvidia.com/compute/cuda/repos/GPGKEY to apt keys."

I sit behind the proxy so wget freezes and can't so smth. To solve this problem i do this:
1) export all my proxy settings to env variables(add to ~/.bashrc)

export http_proxy=http://usr:passwd@host:port/
export FTP_PROXY=http://usr:passwd@host:port/
export ftp_proxy=http://usr:passwd@host:port/
export https_proxy=http://usr:passwd@host:port/
export HTTPS_PROXY=http://usr:passwd@host:port/
export HTTP_PROXY=http://usr:passwd@host:port/

2) but this script run under sudo so you need that this variables should be saved. To do this run sudo visudo and add

Defaults        env_keep +="http_proxy"
Defaults        env_keep +="https_proxy"
Defaults        env_keep +="HTTP_PROXY"
Defaults        env_keep +="HTTPS_PROXY"

After this it should be working.