ISOBuster = Fantastic!
I had (my Dad actually) had a Pioneer DV-645H DVD/hard disk recorder which eventually had all sorts of errors with recordings freezing and being corrupted. We gave up on it a couple of years ago with a few movies still on the HDD. I read this thread and the one on Videohelp, took the lid off the DVR-645, pulled the HDD out, which was IDE, bought a Simplecom IDE to USB adapter and
ISOBuster and I got the movies off with a few clicks; the movies on the HDD show up as MPEGs which I just copied off to another drive. Windows would not "see" the drive, except in Disk Management, and the data was inaccessible to Windows.
Buy it!