It is most likely a result of software/firmware updates being automatically pulled down from the Internet...at least that is what Vizio says.
Things like the widgets and other applications which I do not use.
In any case, I noticed when I plugged an ethernet cable directly into my TV, it began happening less frequently. I'm back to wireless now and to be honest, it may happen twice a month. Not sure if my Vizio was just far behind on updates or less coming out.