[guilmxm]

@FernetMenta Sorry i haven't see your answer before...

In fact, i could even observe it with ipw (with X11 stopped to avoid any issue related to X11 taking the device as a keyboard)
When you press one key, it can result randomly in no action or repeated actions, sometimes quite infinite, sometimes just a few, and sometimes nothing.
The same behavior is off course observed inside XBMC

To all, i finally solved my issue by blacklisting the module "ite_cir" which is corresponding to the internal receiver module automatically loaded by the kernel, as you can see in dmesg:

[ 14.780621] ite_cir: Auto-detected model: ITE8704 CIR transceiver
[ 14.780628] ite_cir: Using model: ITE8704 CIR transceiver

After a reboot, everything is working like a charmed ! So my conclusion, is that even if lirc wasn't taking in charge signals coming from the internal receiver, this seems to generate unwanted behavior (or interferences i don't know).

You could also deactivate the internal receiver inside the UEFI, but if you do so you won't be able anymore to power on the system using the remote.

TO CONCLUDE: There is 2 more important steps to avoid any issue

1. Ensure X11 does ignore the external IR

Some updates will overwrite the /usr/share/X11/xorg.conf.d/10-evdev.conf, if overwritted X11 will also consider the device as a keyboard.

You can ensure X11 is ignoring the device in X11 log file (/var/log/X11/xorg.log) with a such message:

[ 12.164] (II) config/udev: Adding input device PHILIPS MCE USB IR Receiver- Spinel plus (/dev/input/event2)
[ 12.164] (**) PHILIPS MCE USB IR Receiver- Spinel plus: Ignoring device from InputClass "PHILIPS MCE USB IR Receiver- Spinel plus"

2. Blacklist ite_cir module to prevent the kernel to manage the internal IR

In my case (running kernel 3.2.0_26 and 27), the module "ite_cir" is automatically loaded at system boot, you can see it in kernel log:

dmesg | grep CIR

[ 14.780621] ite_cir: Auto-detected model: ITE8704 CIR transceiver
[ 14.780628] ite_cir: Using model: ITE8704 CIR transceiver

I had to blacklist it:

edit : "/etc/modprob.d/blacklist.conf" and add the line:

blacklist ite_cir

And reboot

THIS operation definitvely solves my big problem and now the remote MCE is working like a charm