Just a heads up, but early last week (last monday or tuesday) i uninstalled a bunch of apps (mostly geolocation apps) that i really don't use often and disabled the "keep wifi on" setting. My phone hasn't had a freeze/unresponsive/appears-turned-off episode since.... or put me in the middle of that river in Glen Echo
Before it would happen at least every other day or up to twice a day with the freezing, or a few times a week with the Glen Echo thing...
Give it a try unchecking the "keep wifi on..." setting, and/or uninstalling a few location apps
The only apps i have in the background are:
Amazing Weather HD
Markets & Me +
and then while i'm driving i'll turn on:
HERE Drive+ Beta
Or when i'm running:
Runtastic PRO