Now you mention it, I think it may have been. Not the programme I was trying to delete - it was a film I'd scheduled more or less to try the system out, and when I started to watch it it said [something like] recording failed, and stopped halfway through.
It seems a bit odd that you can't delete one programme while you're watching another; do you get a warning that there won't be room when the disk is almost full?
We've just migrated from Sky+ and we're really pleased with the FoxSat, but one thing I miss is that the Sky+ has a great big red light that shows up while it's recording. Deleting programmes is more complicated on the FoxSat, though that's often an advantage - you don't press the wrong button and remove Someone's Favourite Programme by mistake!