I didn't have this exact same problem, but I had a problem where all of my EUDs were corrupted and any map I opened with the editor was instantly corrupted. So I just reinstalled it and it worked fine.
Ultraviolet -- Inf, we've got a job for you. ASUS has been very naughty and we need our lil guy to go do their mom's to teach them if they fuck around, they gon' find out
UndeadStar -- I wonder if that's what happened to me. A returned product (screen) was "officially lost" for a while before being found and refunded. Maybe it would have remained "lost" if I didn't communicate?