Keybaord layout randomly changing in FFXIV

I've been having this issue for ages. Sometimes the keyboard layout in FFXIV randomly changes. I'm assuming it's caused by me hitting some key combination but I have no clue what the combination is to revert it back. The only way I know of to revert it back to normal is restarting the client.

It's not the same one as used in Windows (shift+ctrl) and when the switch happens it affects FFXIV only. Does anyone have any clue what the key combination it is?

Yes it's ALT+ SHIFT which switches keyboard layout. If you are on windows 7, you can disabled it in this way:
Control Panel => Region and Language => Keyboard and Languages => Change Keyboards => Advanced Key Settings
I just disabled all type of combo keys in that window