Disconnecting a drive while data is being written isn't a good idea. Some problems should be expected. I expect any serious ones will be addressed. Unless the "live buffering" feature of the DVR is turned off or the receiver is turned off (standby) there is always something being written. Perhaps they need a "disconnect USB" option on a menu? They certainly need better recovery for when a drive is disconnected than what Jim5506 reported (if that experience is common).