When I started Task Coach today after I did not close it properly (had to kill the X session, not Task Coach's fault) all the changes I made to my task list were gone. I have a .bak file from before I made the changes yesterday and I have one from just now. But the changes I made yesterday do not seem to have created a .bak file.
Also, I happen to have a backup of the .tsk file created last night (ie after I made the changes, but before I terminated Task Coach). This file is nearly identical to yesterday's .bak file.
‘Auto save after every change’ is enabled.
Let me add that I spend quite some time adding new tasks to Task Coach (and removing them from my old to-do list application) yesterday. All the work was in vain. I am quite angry at Task Coach now, because, no, I did not hit the save button, but I was under the impression that this would not be necessary with the auto save and backup functionality in Task Coach taking care of that kind of stuff.