I've been having this same issue. Googling for answers says it's a DEX issue, but when I tried to disable DEX for FFXIV, I get the message that it can not be turned off for this game.

I've uninstalled and reinstalled nVidia drivers, I've run scan disk, I've even tried the password change that I've seen mentioned.

I'll try uninstalling and reinstalling the game, but everything I've read says that doesn't actually work, so I'm not terribly optimistic about that solution. :\

I have not been able to play the game for about four days now, due to this repeated and constant crash.

Here are the problem details I keep getting:
Problem signature:
Problem Event Name: BEX
Application Name: ffxiv.exe
Application Version: 1.0.0.0
Application Timestamp: 54e55fa0
Fault Module Name: ffxiv.exe
Fault Module Version: 1.0.0.0
Fault Module Timestamp: 54e55fa0
Exception Offset: 00183a6d
Exception Code: c0000409
Exception Data: 00000000
OS Version: 6.1.7601.2.1.0.256.1
Locale ID: 1033
Additional Information 1: 2438
Additional Information 2: 2438a47ab7689067ed07cfbbbcfed5c2
Additional Information 3: e2c5
Additional Information 4: e2c5287919c13f7285bd89c214951537