I have a stable and trouble free HR20-100 with WD 1TB Green drive in an Antec MX-1 case. The other day I got IKDs for everything I recorded in a 12 hour period. I found the problem was that power to the eSATA had become disconnected although there was nothing to show this on the HR20-100. It would merrily let me schedule things, indicated shows were recorded, and watch live programming. Absolutely no indication the hard drive(s) were gone.
My fix was easy but makes we wonder if others problems are related to a glitch that somehow removes the hard drive from the system.