The preview doesn't seem to let you go further than page 12, so I can't say for sure, but that explanation appears to be a smoke screen to hide the fact that it is in fact a copy of Calculus: Early Transcendentals. The copyright page is definitely taken from the original textbook and the table of contents appears to be as well.

Yes, most of them probably just didn't notice the reduced battery life until this warning brought it to their attention. When I upgraded my notebook's Windows partition to Windows 7 I started getting this message, but I started seeing the warning over a year before, whenever I booted Ubuntu.