Disable keys in remote control

When I'm watching a video if "next" or "previous" button is clicked with the mouse XBMC freezes. The problem is that I have a HAMA remote control and the keys "channel up/down" are mapped to that functionality and it's quite easy to press them.

So, Is there any fix for that problem?. Or, can I disable those keys?

I've been editing Lircmap.xml and remote.xml (in /usr/share/xbmc/system) without any luck.

Thanks in advance.