So for instance, if you wanted to press the GUIDE button on your remote, but you always pressed the EXIT button first... do you think it would ever not bring up the guide?

What I'm guessing here, and just trying to isolate, is that the remote probably drops in to a low power mode between keys strokes. When it wakes up out of that low power mode it might be doing it too slowly at times to detect the button that was pushed.

If this is the case then, then I imagine longer pushes would tend to be detected anyway, and anything you could do that'd keep the remote awake and in a higher power state would tend to eliminate the problem. So for instance when the backlight is on, the remote is minimally thinking about when it needs to turn the backlight off. This is all conjecture and guess work without any knowledge of how the remote's software actually works, but it's seeming plausable.

Try holding the buttons down longer and see if it ever misses ...

Oh, and if I'm right this may very well be an issue that can be fixed in the firmware. The firmware may need to be rewritten to check the keypad more quickly and any debouncing done in s/w may be to be reduced.