Well, if you have a Windows RT devices and have installed Windows RT 8.1 Preview, can you do me a favor ? please check if you have this file "C:\Windows\System32\mrt100.dll", and if there is, please upload it, thank you very much !
I would, but I don't know if we are allowed to share system files from a OS on MDL. I'm running Windows RT 8.1 Preview on my Surface RT 32GB, you can download it by going to the same webpage everyone can get the preview isos from, but obviously must have a RT system running for the webpage to detect and offer this version.