I just downloaded Action as a trial. Since installing Action Battlefield 4 crashes when trying to join a server. This happens whether Action is started or not ever since it was installed and then started.
If I un-install Action, there's no difference.
I have to un-installe Action and BF4 and then re-install BF4, and then BF4 it works as expected.
If after re-installing BF4, I re-install Action, without starting it, then start BF4 and join a game (switch to a different window out of BF4 (without ending the game) I can start Action and it works.
If at any time I start action before BF4 is started and a game has been joined, BF4 crashes (Windows pop-up says that the program BF4 has stopped working) and it will not work again until I un- and re-install BF4. This persists even if I re-start window.