DSR704 Locking up - DirecTV DVR

For DSR704 Locking up, relating to DirecTV DVRs and receivers. Had this Phillips unit for approx 2 years now. Worked fine until DTV uploaded a "patch" to display multiple programs of the same series in a folder format about 1 year ago. Since then the unit locks up and we have to unplug the power cord from the unit to reset it. This is becoming more frequent "feature"!

Does anyone know if this is a common issue with this unit, or fault after the software upgrade? Can this be fixed by reverting to a 'default' or 'factory settings' option?