OpenMPT should of course not crash. However, when it does, and it has control over the crash, it will create a backup of all open files and it will notify you of the location of those backup files (they are located in %TEMP%\OpenMPT Crash Files).

Furthermore, if you disabled Autosave, it's your own fault. OpenMPT by default automatically saves backups every ten minutes, and you can increase this to save even more often.

Last but not least, we would like to know more about the crash. When does it happen? Do you use any VST plugins (by far the most common culprit for crashes)? Is a memory dump (.dmp file) created in %TEMP%\OpenMPT Crash Files? Without this memory dump, it will be hard to analyze what happened. See also the FAQ on creating memory dumps.

Meet a custom alternative tuning, "Period".
It's General, all pitches are 1 and all pitch numbers below 0 and above 31 are called ERR, and 0 to 31 are called by their numbers. It's supposed to mimic number of samples for 8000Hz with sample for each pitch. After I finished it, I tried it. I tried to press octave key (number) on this tuning. It crashed, I could not use it, I could only end Windows warning with closing the program. Because of crash, the biggest problem that will ever exist occured. That is, all 32 samples are deleted forever and tears are placed on my eyes.

Thanks for the detailed description, I can reproduce the issue now.

By the way, you do not need to use a custom tuning for your purpose: Instead of creating a tuning where each sample has a ratio of 1, you can instead use the Note Map of your instrument and set the first column of all notes to C-5. Then all samples are played at middle-C.

Please do not change the priority of the bug, this is up to the developers to decide (and "immediate" is not the correct priority for a bug that can be easily worked around).

Since I was able to reproduce the crash I can also say that in this type of crash, your module is not lost. As said before, you will find a backup of the module in %TEMP%\OpenMPT Crash Files. You can copy&paste this path into Explorer to find the files, although OpenMPT should have opened an explorer window on its where you can find the file.

Fixed in r8743.

Sorry to say, but I DO need a custom tuning. Otherwise the names won't be correct (numbers 0-31, ERR for outside range)

And I use Windows, not Linux. So give me .exe installer, not source code.

I did not expect you to compile the sourcecode yourself, the code revision is only mentioned for our own housekeeping. The fixed build was simply not available at the time of writing. You can now download it from https://builds.openmpt.org/builds/auto/openmpt-win32/

The next stable version will most likely be released this weekend.