Old but still relevant.
In my case, I got everything up and running but every 30 seconds (or so) my kodi video would skip backwards. Tried using smplayer which is also programmed through flirc with my harmony remote. Same thing. I then noticed as I started to research the problem that my browser would scroll to the bottom of the page without any input. I thought my mouse was scrolling on its own until I figured out it was a page down command and not a scroll event. (Thanks xev)
I moved my flirc from a 10' male > female extension cable that allowed me to perch it up above the cabinet for a clear view, and plugged it into the same hub the extension cable was plugged in to. Problem gone. The cable is still fairy new and well reviewed, so I'm not convinced the problem lies there yet. I'm wondering more if it's acting like an antenna through the cable, or if It's picking up stray signals from where it's placed. Either way I'll try and update this if I make any determinations.
Of course I'm open to suggestions as well.