I too have noticed this behavior. Do either of you guys have a receiver that the ATV is going into? I asked because I've noticed what has caused mine to get hung up like this.
I noticed that If I put my ATV to sleep *before* switching the receiver input (say to sat. or whatever)... and then make sure that the receiver is set to the ATV input *before* waking the ATV back up, that the ATV works fine.
However, if I change the receiver input before putting the ATV to sleep and then later try to go back to the ATV by switching the receiver input back to the ATV, it then hangs up 100% of the time. I can only get it active again by physically unplugging the thing... pretty freak'n annoying. 😡