CNR was not working for me -- I tried all suggestions without success -- I noticed the following line in the shell output when I attempted to update-install the cnr-client:

id: cannot find name for group ID 100

I looked up "group ID 100" and found a reference to the file at ~/etc/group that led me to discover that it had been somehow rewritten without the following line:

users:x:100

I opened this file in KWrite and added the missing line, saved the edited file, and entered into the shell:

sudo apt-get install cnr-client

and L0! it installed correctly, CNR synchronized with CNR.com, confirmed, and is now functional.