I was loading an auto-save and had a crash. See below log details:

0.003 2016-04-19 22:39:36; Factorio 0.12.29 (Build 17931, win64, steam)
0.003 Operating system: Windows 7 Service Pack 1
0.003 Program arguments: "C:\Games\Steam\steamapps\common\Factorio\bin\x64\Factorio.exe"
0.003 Read data ...