DVR

DVR not recording all programs. Monday night at 9 pm I had 4 programs set to record. One recorded fully. One recorded 1 minute of an hour show and the other two shows never recorded at all. Then Tuesday night I had 6 show schedualed to record and nothing was recorded. Tonight I had two show schedualed at 7 pm and nothing was recorded. I have just went in and rebooted the dvr. I have one more show schedualed for 9 pm tonight. Hopefully it will record. What could be causing this problem. Do I need a new dvr?