After doing everything I fixed the problem you are having. The early access client I downloaded and played starting giving me ...has stopped working... window every time I loading into the game. I received an email with a link to download the client for preordering but disregarded cause I already had the client downloaded from early access. Seeing how I tried everything..my last attempt was to uninstall and reinstall using the NEW email link for the client. Now no more problems with ... has stopped working. Played my first full day without problem.

Short story, if you are getting Final Fantasy XIV has stopped working, uninstall and reinstall. Worked for me. Hope this helps!