Great question, this also applies to Vista and likely Windows 7 too.
I've always assumed this was by design, albeit pretty poorly implemented.
You tell Media Center that you want to record 'The Goonies'. Fine, it says, and schedules it. However, after you've watched and deleted the film Media Center still thinks you want it to
Record 'The Goonies'. So, four months later when the film is re-run it does just that.
I've actually caught some good TV/films recorded in another showing after they were deleted automatically to free up space, so it's not a wholly useless approach, and it is this 'catch it again if it is deleted automatically so you get a chance to see it' thinking that I assume is behind the behaviour.
I think there should be a global setting so that when an item is deleted you get a choice of:
- Delete programme and requirement to record same
- Delete programme and ask if you also want to delete the requirement to record same
- Delete programme but keep requirement to record same
I'd be interested to see if there is a registry key etc. that would modify this behaviour though.