I think I see where your heat problems are coming from.
It probably will call for heatsink modification.
This Site did an excellent job documenting how to do the heat sink mod. Easy, follow-along directions and pictures for how to do it for the non-technical/not alot of electronics repair crowd.
Since I did the mod on my original Roku, it's not locked up or frozen a single time. That Roku is out in my gazebo attached to a small 24" LED TV that I use to watch baseball games or football in the early to mid Fall.
I expect I'll repeat that mod on my Roku 3, but I'd really like a device that has an extra storage slot and a USB port on it for movies/photo's. The Amazon Fire fits that bill, I'll probably look at the Apple TV device too.