It's possible that the drive is fragmented. Check in Menu > Set-up > Help, option 9 "Disk" should show more that 15% free. If not the box will not work properly. The only way I know out of this is to re-format the drive. Menu > Set-up > Help > Green Button > Blue Button. You will lose all contents of the disk but it should cure the freezing issue. You also will have to re-scan for channels.
JES
July 2009