My GS100K seems to turn off or "go to sleep" after 5 mnutes of inactivity. I imagine a powersaving mode or whatever, but it happens even when hooked up to direct power...is there a menu option hidden amonst the menus?

Remove the tape.

Changing the auto off setting is not an option. You can work around it somewhat by using "quick start" - press the little button behind the mega ois button and next to the scroller: a green light should show (to turn off "quick start," press the same button again). Gives you less lag time to recommence shooting if your cam has nodded off. It does, however, drain your battery to keep "quick start" on. On the other hand, I have kept it on for six-eight hours using the waist pack battery and the battery has held up.