Comment 13 for bug 1667512

atom's suggestion to stop all disk operations was the key to fixing this. I had a ddrescue operation going on in the background that I stopped after reading this thread, and BAM it started moving up from 37% and eventually finished.

Basically, this issue affected me as well on Ubuntu 14.04 x64, when trying to update my nvidia drivers from graphics-drivers ppa. I did 'sudo apt install nvidia-384' and it was stuck at 37% saying 'update-initramfs: Generating /boot/initrd.img-3.13.0-144-generic' for 20+ minutes. At that point I went to /boot/ and saw that a 'initrd.img-3.13.0-144-generic.new' was sitting around with a 0 file size since 20 minutes ago. Something was stuck but I didn't know until reading this issue.