Good afternoon and thank you for the reply!

When uninstalling the game, could you delete all remaining Final Fantasy XIV files from the PC? You mention that the game crashes when other programs are being run at the same time. Could you try running Final Fantasy XIV by itself to see if it crashes? Also just for testing purposes, please try disabling the anti virus programs running in the back ground and then launch the game. Additionally please try downloading the game with a wired connection.

Please keep us updated and hope to see you online!