If you’re using MDT to deploy images, and the deployment crashes or you for some reason abort the installation in the middle of the installation; you might get a lingering installation. So when you retry, you get the “LiteTouch has encountered and Environment Error (Boot into WinPE!)” error message.
This is because setup detects that there is an installation in progress, and decided to about (specifically, it reads the c:\minint folder).
If this is a clean install, simply press F8 once you’re in WinPE, to bring up a command prompt, and run diskpart to wipe the disk:
SELECT DISK 0
Re-run the installation, and all should be hunky-dory.