Everytime I unchecked it, it came right back on when I'd go into it.
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I had this problem too. Did you try doing a complete fresh install? There was one build that I could not shut off but that was a while ago. I switch back/forth between the dark version and the nightlies on carbon-rom. Both now are able to shut off for me.
Perhaps - do a good wipe (dalvik / cache, etc) and see if that fixes it. If not, reinstall fresh, no dirty installs. One of those steps should work. Good luck.
EDIT - also, if you are testing unchecking it, I'd be sure to clear the recents list too. Sometimes I get in more trouble with the recents hanging around then lots of other stuff.