Here's a little tip I have learned because my computer "sputters" sometimes as well. There is a check box for "Loop" in the toolbars. Uncheck that for all of your songs. Then at least when BIAB reaches the end of your composition it will stop, allowing you to exit normally or do a save of the work you have done. Before I started doing this when my machine would bog down I had no way to exit except to force it to close.