That looks extremely weird to me...
Can you give me some more information? Like, your health after the final boss, things like that.

Here's the save:
https://drive.google.com/file/d/0B-djc8k7dnB0OG1CWkgxb3Z5OXM/edit?usp=sharing

Here's specifically what happened
- beat Death... Maybe had a heart left? Can't remember.
- talked to her
- credits roll
- allowed for game to be saved/reset to go to New Game+
- character spawns at the beginning of the game but falls through the map

And that's the state that the save is in. But instead of falling through the map, you die on spawn. I've tried over and over again and it's always the same.

I managed to simulate it happening with my other save, too! I teleported back to the beginning and immediately fell through the map, dying. Since the actual save is at another location, vs the New Game+ state, I can still load the save. It doesn't happen always, so tricky to track the trigger.

I'm wondering if there's a weird collision box problem that happens on spawn in the start area?

I'm actually still having issues with sound and music stopping. There seems to be some sort of crash log cut when things go haywire, so here's an archive of the those:
https://drive.google.com/file/d/0B-djc8k7dnB0MTZDMlZJZ3REbHc/edit?usp=sharing

Honestly, I can't recreate that no matter what. What happens after new game+ is simply a warp back to stage 1, so whenever you try to warp to stage 1, the same code is run. And that makes sense, considering you said your other save also has this problem when you warp to stage 1.

You mentioned your audio driver problem before, and the software I use tends to do weird things when drivers etc arent working properly. I wouldn't be surprised some random collision would stop working, things like that...

I will keep investigating, sorry for this inconvenience ):

Tried thousand of times, in 4 diferent versions. How the heck were you able to do that?

Just to be clear, you're both saying that you copied my save onto your PC, and it doesn't do the die-on-spawn thing?

No, you do die. I actually know why it happens, it just can't be recreate on anyone else's computer following your steps. I'm just guessing the game goes insane for some inconsistent reason, which is very unfortunate, really.

Basically what happened is: you beat the game, got warped to stage 1, the ground didn't load, you walked a bit and fell into the void and died. The game saves right after the warp animation finishes, so your position was saved inside a piece of ground that doesn't load on your computer.

I tried your save and you spawn INSIDE THE GROUND. The fact that you die instantly is because that ground isn't loading on your computer and you are just falling to death. No idea why, though.

I'm not sure how likely this is to happen, but it could be a damaged file. Try using the "check game cache" option

This should be a hidden achievement

I've run inbto the same problem but found a simple solution for anyone in the future that might need it. Simply go into the local files of the game from there on to "Momodora III\data\saves\slotX" X being the number of the save thats broken. Then just change the value that goes out of bounds (should be the 9th line, for me the value was -999), to 13. After loading you should be back to the spawn. If that didnt work just start a new game and use that save data as a reference to find which value is bugged.