You beat me to it.
Last night after finishing looking at a VHS tape I made while out of town, I went to set a timer for next week, which I had to over-ride, and then decided to check "Menu, Daily Schedule (7)" and sure enough, I still have everything for about 2 months.
So I retract my earlier statement, "You Learned me something new!"
I believe this Daily Schedule and list of what is on the HD is used in trying to smooth out recording options. When you select something for recording, if you select the same item at another time, it won't work.
I had that problem recently with trying to record 24 on FOX. There were going to be to back to back shows, but the listing for each show was the same and included the info for both shows, so the timer cancelled for the second show. I caught it and did an over-ride. Then a week ago, same thing, but Fox ended up changing programming and did not show the second show, but the first one was recorded. Now the second one will be playing next Friday and has the same info as the one on my HD, so the timer doesn't set it because it thinks it's already on the HD. I happened to check it and was able to do an over-ride.