I was having the exact same issues reported above. Upon further investigation using Event Viewer I was able to determine that there was a System event every time the patch failed. Taking a look showed something similar to this in every single event that matched the timestamp the patch failed "Process C:\Program Files\AVAST Software\Avast\AvastSvc.exe (process ID:1232) reset policy scheme from {8c5e7fda-e8bf-4a96-9a85-a6e23a8c635c} to {8c5e7fda-e8bf-4a96-9a85-a6e23a8c635c}"

I disabled Avast and was able to download, patch, and launch FFXIV without a single issue. I reactivated Avast after the download and have not had an issue since.

Hope this helps or at least gives you another tool to help TS the issue. If you need to know how to launch Event Viewer - this link will assist. https://technet.microsoft.com/en-us/...(v=ws.11).aspx