I don't have the problem you have, but I can confirm that "du1" has something to do with HDCP. Thankfully my setup is pretty robust, and i can turn on my receiver, box, TV in nearly any order and everything syncs up right, w/ HDCP. If i turn on the box, then when the TV comes on, the box flashes "du1" real quick. Then it will do it again when I turn on the receiver(which i have the box running through, HDMI in and out). Or if i switch back to the input on my receiver that I have the box set up for, the box will again flash du1 real quick. So it has something to do with syncing up HDCP.
This confirms that obviously this will not be an issue with component since it is an analog connection and has no encryption. Channels are pushing cable co's to disable component outputs... in this day and age they want any port that outputs HD to be protected: 1394(5C), DVI/HDMI(HDCP), etc. However there aren't any consumer devices that input component HD and record it, yet... there is a thread somewhere in here about a device at CES that does just that, and re-encodes into digital on the fly. I think Hauppage will make it.
I turn my box off(I know I know, you shouldn't... but it does stop the buffering of channels, no matter what you tell me, I know this is true) and have never had this issue.