I did some testing with diffrent CVS version on this one and tracked the malfunction with firedtv (dloppydtv) remote to days between 23st and 25th of january, 2006. The earlier version works with the remote just fine as the latter does not. Here's an extract from the changelog:
MediaPortal Remotes
On 23/01/2006 [09:16:45] mPod added the following change: cleanup for Hauppauge remote config, added tooltips to reflect slider values
I've got the same problem, but found a solution. A nice bloke at firedtv.com has written an alternative remote control app to the one that ships with the fire/floppydtv. This allows keystrokes to be sent to any app, including media portal, in response the remote being pressed.