This reminds me of an issue I have with a particular MCE system and the MX-900. Using the *built-in database codes*, pressing any key results in the MCE system sensing multiple presses. Press "left" and it goes between 1 and 3 positions left. The stock MCE remote works fine on the system, and an MX-850 using database codes controls the system fine too.

URC is having trouble duplicating it... and the only solution I've found is to turn off repeating codes and keep the number of repeats to "2" (1 is generally ignored, and 3 still results in multiples). So I can no longer hold a button down to go through things, but at least I can now actually select things on the menu, and pressing the 30-second skip button no longer randomly instantly skips to the end of the video (what a pain that problem was).