I have the same problem. After a look into my WinEventlog i found following Log
Faulting application name: Launcher.exe_DCS, version: 1.2.7.23097, time stamp: 0x52b97dcf
Faulting module name: DXRenderer.dll, version: 1.2.7.23097, time stamp: 0x52b97863
Exception code: 0xc0000005
Fault offset: 0x0000000000024c8b
Faulting process id: 0x1f2c
Faulting application start time: 0x01cf194a2857df9b
Faulting application path: D:\Eagle Dynamics\DCS World\bin\Launcher.exe
Faulting module path: D:\Eagle Dynamics\DCS World\bin\DXRenderer.dll
Report Id: 6c98617c-853d-11e3-970c-c86000c29f59
Done a uninstall and reinstalled 1.2.6 without the Moduls and run the update . Same in green.