Hi Richard we had the same problem as you with our Thompson box and rang there help line and ws told to go to the help menue and punch in 1397 and was able to delete the frozen programme. You could try that to see if it works for you or if it doesn't call the help line the number is 08444 159 159.
Hope you get it fixed ok but it did seem odd to me that we have both had the same kind of problem with the same make of digibox hey. the engineer said the programme that was recorded was corrupt on ours.
Pat
January 2009