There have been many threads posted here on this issue. As others have mentioned, Dish should give us the option of deciding when to do the nightly update. When I had the 722K, 722, and 622 VIP receivers, I could set the time when the receiver would do the update. With the newer Hopper, you can't do this.
I am usually watching TV at the time that it wants to do the update. If I happen to be away from the TV at that moment, the receiver re-boots and I miss a part of the show that I was watching. This is extremely annoying.