My TiVo HD froze up this morning. When I tried rebooting I get the "Powering up" screen for about 10 seconds, and then it immediately goes grey when it would normally switch to the "just a few minutes more" screen. I unplugged for 30 minutes and then tried again, but still cannot get past the grey screen. The fan is working but I do not hear the hard drive spinning. Thanks for your help!