Sony dvd recorder rdr-hx780 + pauses every minute

Hi. we have purchase a couple of months ago a sony dvd rdr-hx780 dvd recorder (last one in shop - was display model). The problem we are having is that we can record a programme from tv onto the harddrive no problem, but for some reason, when we watch recorded programme it pause every minute for a couple of seconds. Tis very frustrating. We have reset it to factory settings according to manual but problem is still there. Can anyone help. It’s not returnable as it was a display model and it has been more than 14 days.