Comment 3 for bug 521289

The relevant error is
===
Setting up boinc-client (6.4.5+dfsg-2ubuntu2) ...
Your account has expired; please contact your system administrator
chfn: PAM authentication failed
adduser: `/usr/bin/chfn -f BOINC core client boinc' returned error code 1. Exiting.
dpkg: error processing boinc-client (--configure):
 subprocess installed post-installation script returned error exit status 1

Has your root account expired or did you lock it with "passwd -l root" ?

Could you please run the following commands, then reinstall the package and tell if it helps
 sudo passwd --unlock root
 sudo usermod --lock root

Thanks.