Alright I've literally pushed every option and button on my keyboard, and I cannot replicate your problem.
I would suggest opening %appdata% or something similar on your version of windows..
C:\Users\Xikini\AppData\Roaming -- my directory.
%appdata% -- copy pasting this into windows explorer should bring you there though.. and make sure you have hidden folder options disabled. check google if unsure.
Anyways!
Uninstall remere's then delete "Remere's Map Editor" from app data, and from program files, so that there is nothing on your computer from Remere's Map Editors previous versions, like settings et cetera.
Then reinstall remere's map editor, and see if it's fixed your problem.
If all else fails, reinstall from scratch and if the problem occurs again hope you can remember what you pushed! -- Xikini's policy on programs that break.