I've just discovered I can manually lock the screen with a quick press of the power button. That works every time but is sort of beside the point. It should (used to) lock automatically when the screen goes off after 2 min.
And...what exactly are the "screen timeout modes"? Each of the two consists of 3 time intervals but there is no explanation or description of what they are/do. Originally they were unselected and I just had the 2 min timeout. So are these deepening levels of power saving (dim, off, sleep)?
I wish there were some kind of reference for the CM settings. It would really help a noob like me