I think I've noticed an early indicator for a crash. I'll make this a poll to see if other people experience it, too. Maybe it will be helpful to you.
A couple hours before a crash, when I click on a page to open it, it will not load... I get a google message saying "page cannot be found". When I click my backwards arrow and try again, it works. This happens with virtually every page I try. Then the board goes down for a couple hours.