I'm here on this forum because I have exactly the same problem!
I bought the box in April a year ago (2012), & have been plagued by this problem. - It appears to be more of a problem on some programs than others.
We have many episodes of "Heartbeat" recorded, with most of them missing the ends.
I have regularly alternated between "Auto" recording, where the box is supposed to change the actual time of recording to match that of the transmission, &
"Manual" - Where one has the option of addding up to 10 minutes buffer at the end.
Neither works! - What might have been a sloution is Auto + the 10 minute buffer, but the box des not allow this option. - A pity.
Now that this box apears to be discontnued, I guess that there will never be a solution?