Update: After resetting the HR24 I was able to format the new WD drive and it is working. I've had a 1 TB external hard drive on my HR24 working since September. The generic eSata enclosure has always caused electrical noise(AC Hum) on AM radios in my house so I purchased a Western Digital My Book AV DVR Expander 1 TB USB 2.0/eSATA Desktop External Hard Drive WDBABT0010HBK-NESN* to replace the old drive. When I followed DirecTV's instructions for adding the new drive, the unit would not recognize the drive and defaulted to the internal drive. After several tries I gave up and hooked up the old drive which it now won't recognize. Tried again several times following the instructions carefully. No joy. Cannot access any of my recordings. As a last resort, I disconnected the old external drive and did a full system reset on the DVR, wiping our the internal drive. I then tried hooking up the old external again. The DVR still will not recognize it. Help please, my wife is really going to be pissed when I tell her we lost all the recordings. Thanks in advance, Joel *Note: When I checked the box on the WD drive, it says it is compatible with HR15, 20, 21, 22 and 23 - no mention of HR24. Kind of strange since the WD drive is a new model and it does not appear to work with DirecTV's latest receiver.