I have my HR21/AM21 combo plugged into a UPS, along with my eSata, stereo and TV. Our power went out at 3:30 today for an hour. The TV, stereo and eSata stayed on without even a flicker just like always, but my HR21 rebooted while the AM21 power light stayed on the entire time. When I used to have an HR20 (no AM21 required) and the power went out, the HR20 never rebooted. I guess the way the HR21 plugs into the AM21 for power must result in a slight delay - enough so that it causes a momentary loss of power to the HR21 and results in a reboot. Has anyone else experienced this? This is my first power outage with the HR21/AM21 combo. Can D* do something via a software update to prevent the HR21 from rebooting in a case like this? If not, what's the point of having it plugged into a UPS?