Like many people, I've had problems installing org-mode using elpa, resulting in the well known error > Invalid function: org-with-silent-modifications This is usually due to not following the installation instructions: > When installing from ELPA, please do so from a fresh Emacs session where no org function has been called. I've encountered this problem a few times on Windows installations, each time through forgetting the above advice. The solution was straightforward, go to (home)/emacs.d/elpa and delete the org file, temporarily rename the .emacs file so that you're restarting Emacs to a completely fresh session (or start a fresh emacs without any customization with `emacs -q` -thanks to iNecas).  After that org-mode installs without a hitch. And then I tried to do the same on Linux.  Same error, same attempted solution. This time it didn't work.  I wasted half on hour on this until I tried a complete reboot of the PC.  This time it worked.  The lesson is, when it says _fresh_ Emacs session, it means a completely fresh Emacs session.