Forced reboot launching editor the first time

Note that before I tried running the editor via the Launch button, I just happened to run the Editor exe directly, and this did not repro then.

After my PC rebooted I tried to reproduce it again and it did not occur, but other testers have seen this happen 1 time before in the last several weeks.

Here is a list of all OS versions this has been seen on before:

• Windows 10 Enterprise 64-bit (10.0, Build 16299) (16299.rs3_release_svc_escrow.180502-1908)
• Windows 7 64Bit SP1 (build 6.1.7601)

(Note, as we're not 100% sure of the repro other than it only happens on "first install" of 4.20, please do not list negative repro cases yet)

Repro Rate 1/3 (occurred on first time only)

1. Install the Epic Games Launcher
2. Install 4.20 version of the engine
3. Click the Launch button

RESULT:
1. The Launch button changes to the word "Prerequisites"
2. The UE4 prerequisites exe appears in task manager twice (2 processes)
3. No prompts or activity occurs, but after several seconds, the PC reboots

Lighting geometry regardless of face normal direction, and lighting that wraps around geometry