AFAIK the IDE first renames bak2 to bak3, then bak to bak2, then the original bb to bak and then saves the new source as the original bb, then throws it at the compiler. No matter when it crashes, some of the backups should remain intact, unless your Systems FAT handling isn't completely messed up. But you cannot blame Blitz for such a case.
As for the collision problem I'd suggest to hide, then position and then show the player before the game starts, because this will remove "collision tensions".
As for the collision problem I'd suggest to hide, then position and then show the player before the game starts, because this will remove "collision tensions".