Thanks for your suggestions.
The output of sudo dpkg --configure -a is nothing.
The output of sudo apt-get install -f is:
Although there is suggestion to remove some packages, I've not done yet. Firs of all I need to know if these can explain the problem I have stated.
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages were automatically installed and are no longer required:
gir1.2-gconf-2.0 libutouch-grail1 libgtkspell-3-0 appmenu-gtk g++-4.4 libminiupnpc8 libvncserver0 libstdc++6-4.4-dev
telepathy-indicator libgwibber-gtk2 appmenu-qt gfortran-4.4 libgwibber2 libtelepathy-farstream2 libfreerdp-plugins-standard
libutouch-evemu1 libutouch-frame1 telepathy-logger python-poppler cups-pk-helper libutouch-geis1 libncurses5-dev libfreerdp1
libssh-4 libreadline5 appmenu-gtk3 gir1.2-panelapplet-4.0
Use 'apt-get autoremove' to remove them.
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
Second concern is that now a days I try to keep the configuration as given to me, without changing anything drastically. I am afraid, modifying (by installing or removing packages) the system may face more problems. This may turn out to be false but am I right to follow this to be on the safe side?