Updated 05/25/2011: Save yourself time, money, and frustration by checking out my latest solution.
I discovered a simple fix for a problem with getting our DirecTV (HR20) receiver to pickup the signal from the DirecTV RF remote. It had been working great since I bought it and was fine until recently. Tonight I checked the batteries, which were good, so I went to the DVR and noticed that the antenna was leaning to the left slightly. I must have bumped it one night when fiddling with the new HDMI splitter.
I straightened the antenna and when I went back to the bedroom the remote worked perfectly again.
Update: This may not have been the real problem. I have an update in Part 2.