root@vmhost:/var/log# apt-get install --reinstall x11-common
Reading package lists... Done
Building dependency tree
Reading state information... Done
You might want to run 'apt-get -f install' to correct these:
The following packages have unmet dependencies:
 pppconfig : Depends: ppp (>= 2.3.7) but it is not going to be installed
 pppoeconf : Depends: ppp (>= 2.4.2+20040428-2) but it is not going to be installed or
                      pppoe (>= 3.0) but it is not going to be installed
             Depends: ppp (>= 2.4.1.uus2-4) but it is not going to be installed
 pptp-linux : Depends: ppp (>= 2.4.2) but it is not going to be installed
 wvdial : Depends: ppp (>= 2.3.0) but it is not going to be installed
E: Unmet dependencies. Try 'apt-get -f install' with no packages (or specify a solution).
root@vmhost:/var/log# apt-get install ppp
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following additional packages will be installed:
  x11-common
The following NEW packages will be installed:
  ppp
The following packages will be upgraded:
  x11-common
1 upgraded, 1 newly installed, 0 to remove and 1133 not upgraded.
411 not fully installed or removed.
Need to get 0 B/365 kB of archives.
After this operation, 780 kB of additional disk space will be used.
Do you want to continue? [Y/n] y
WARNING: The following packages cannot be authenticated!
  x11-common ppp
Install these packages without verification? [y/N] y
Selecting previously unselected package x11-common.
(Reading database ... 248371 files and directories currently installed.)
Preparing to unpack .../x11-common_1%3a7.7+13ubuntu3_all.deb ...