Hi Yawor. Totally off topic, but I used to live down south of you in Raciborz. I haven't been back in years, but miss it very much. Back to the Flirc...
I have a used several remotes with the Flirc while experimenting. All worked fine, and are not the problem. And I have "cleared configuration" back to factory defaults over and over.
I only have one Flirc, and I intend to leave it and use it in a FireTV.
The problem is that by default, Flirc responds to IR signals sent out by various MCE remotes and there is no way to turn it off. And since I have an MCE computer in the same room, whenever I try to control my computer with the MCE remote, the Flirc that is plugged in to the FireTv responds to the signal as well. I press "up" on my MCE remote, and the Amazon FireTV moves up as well as my computer. I have tried this with my Harmony 350 programmed in MCE mode, and with an HP remote that came with an old MCE laptop. The Flirc responds to both and I cannot stop it.
To make sure it wasn't something wrong with my unit or what I was doing, I walked across the street this morning to my neighbor who has has a Flirc and had recommended it to me. I pointed my MCE remote at his Flirc/FireTV combo, and sure enough it controlled his as well.
Hence, like you said, it *should* not respond to the RC5 protocol used by MCE remotes, but it *does*.
Now, how do I fix it?
Thanks!