Whole chunks in my game world have been replaced with brand new chunks. In addition, individual blocks in certain other chunks have been changed into other blocks, usually ore or dirt and, in one disastrous instance for my storage room, lava.
It is the only game I have been playing since purchase. Whenever there was an update it would cause chunk errors, e.g. noticeable breaks in biome and elevation, but only on the edges of the explored area. This is the first time I have had a chunk error in the core of the map specifically right in the middle of a castle I have been building for a few years. Using Minutor to look at the map I identified that three chunks total have been replaced.
Since I was not playing in creative mode it has been rather difficult for me to accomplish everything up to this point and this glitch might be a game-ender for me. I hope that there is a way to recover the lost chunk, or at the least make a change to ensure that I wont lose more of the world if I continue and repair the world manually.
Fortunately, since my structure was mostly symmetrical I have examples of what the structure used to look like and how it changed in screen shots. I am including a shot of the two replace chunks in the random locations and then the chunk inside the main structure. I have a picture of what the wall used to look like and now. Lastly I included a shot of a section of wall randomly replaced with ores.