Hi
I'm just setting up a new site and encountered this logout by Admin issue again. I tracked it down to the checkbox in the CB login module, which deals with "Remember me". I had it selected to "Hide checked" and this was preventing Admin from logging any users out, plus they were not logged out by session expire either. I checked the other install I had problems with and changing this setting solved the problem, so it was confirmed on two Joomla installations. I'm not sure if this is expected behaviour, or whether it was down to a particular combination of extensions/settings, or if it is a bug, but it is certainly worth flagging up as other Admins could go through the same stuff I did, and it wasn't great.
Thanks