Pretty much what says in the title.

I was playing for a short while earlier on and I noticed my GPU temperature was rather high so in doing so, I logged out, closed the game and then I shut down my computer and let it cool down a bit. After about 20 minutes I turned back on my computer to notice that, from steam, the launcher was uninstalled and so was the entire game. I am now in the process of redownloading it again. I have A Realm Reborn, Stormblood and Shadowbringers.

Does anybody have any idea as to why this may have happened.
Thanks.