It doesn't look like any crash logs saved. Or if they did, they expired? (If that's something that happens.) If it crashes again, I'll check for them right away though.
I got a blue screen error when I went to check my achievements. Wild, alright. Here it is:
Error
gamestates/gamestats.lua:163: bad argument #1 to 'sub' (string expected, got boolean)
Traceback
[C]: in function 'sub'
gamestates/gamestats.lua:163: in function 'switch'
gamestates/menu.lua:197: in function 'keypressed'
gamestates/menu.lua:232: in function 'mousepressed'
main.lua:126: in function <main.lua:125>
[C]: in function 'xpcall'
I released a new update that should fix the achievements crashes, anyway.
Messing around with your save file I couldn't get any silent crashes to occur, though. Do you happen to remember what you might have been doing or what might have happened soon before the crashes? Your save file was on level 3, were they any more/less frequent on any of the levels?