ITOS2007 was made for the N800. It does not know of the clever magnet in the 770's cover and the sensor in the 770's body and the resulting power management. You need to turn things off manually on the N800.

2007HE is a version that runs on the 770, but it still runs the N800 way, and ignores the cover. You need to use the power button menu.

(Yes, this is stupid, everyone has said so already :-)