WELL! I am very happy to announce that my problem has been solved. I found the answer browsing around the internet, searching for possible solutions in forums etc. Turns out the TrackIR USB plug has to be unplugged at the time you install the software for it to work... I have no idea why this is, but it solved my problem anyway. So... no more time to hang around this forum - my hat is already on, it's time to launch Flight Sim X for some serious FUN!!

:)
Harald