Denford seem to be a UK company http://website.denford.ltd.uk and they have a forum http://www.denfordata.com/bb/index.php. It would definitely be worth asking on the board - on a cursory look I couldn’t see a mention of Kicad but I did note that they specify metric units so using imperial is a red herring. Have you applied any updates? These sort of problems may have been fixed in more recent software versions. Excellon is a universal standard and I am not aware of any major pcb supplier having any problems with the drill files produced by KiCad so it is more likely to be a limitation of the Denford software.
PS Your caps lock seems to be stuck …