I have a 4 year old 722. Just over the past couple of weeks the unit has displayed the "Hard Drive Failure" error message with some frequency (every 2-3 days.) There have been no changes to hardware's location or surrounding theatre equipment and there is no glass enclosure to impede ventilation. So I'm wondering if this is a sign that the hardware is truly failing and that the hard drive is about to lock up completely - or - There was a bad software update that is causing the instability. Unplugging the 722 has, thus far, always restored it to full functionality. It's also been very temperamental when trying to delete a program while another is being recorded. When two recordings are occurring and I delete a saved recording, I will almost inevitably get a "Signal Lost" error message. And on more than one occasion, when only one program is being recorded and I delete, the dreaded "Signal Lost" error will be displayed.