Cannot partial delete one specific recording? Please help
 

I have a panasonic dvd recorder with freeview, I need to partial delete a particular recording but whenever I try from a certain point 1hr 18min I start the partial delete but when I click the start option to begin the partial felete the recorder just freezes and won’t accept any commands eg. start pause etc then within minutes it will suddenly shut down and go into standby, I have partially deleted other recordings so why can’t I do it with this one, I cant even play it past this 1hr 18 properly as it does the same thing. I even tried to divide the title so I could at least salvage one of the 2episodes recorded but although it allows me to go through the commands start divide etc it says dividing but then reverts back to the title page where all the recordings are and the title is still undivided? I hope someone can help as I am trying to record a series of something and its not available on demand so if its unable to be edited I may as well not bother as this recording holds the first 2 episodes