I'll try to explain it :
to start my projects, I used large modules with lots of samples (xxx Mo), in which I after cut new modules, then save and clean. it happened several times on the first large modules, not on the small others.
1.20.01.00 version only, no problems with previous versions.
it looks like "Windows" crashes. no crash report or file, it crashed before.
i use only portable versions of OpenMPT (on several drives) without autosave (i always work on copies).
[in this case: intel dual core, 2 GO ram, win vista 1]
this crash-notify.dmp file will help ?