It seem at first to me that your processor may be on knee
having pain to process the sound but it could be something else.
1600x1200 seem a bit high to me for a 850 (I'm running 1184 on a p4 1.7 ghz ti4200 128mo)
Orbiter seem to "eat" process time, it run well but doesn't let many place for other process.
please try those and feedback how it goes:
-try to lower the resolution and see if the click disappear or lessen
-try to reinstall directx
-try to lower the hardware acceleration of your sound card
-feedback how many FPS you have when the click occure.
I don't know the phillips card and how it handle directx
but I know I had big trouble with kxdriver "zero latency"
especially done for midi music (vst cubase) I had to deinstall
them so I cannot do music and programing orbiter in same time
![:sad:](http://orbiter.dansteph.com/forum/Smileys/orbitersmiley/sad.gif)
So this could have something to do with the buffer size, latency etc etc
of your souncard. Do you have some setting that you can alter
as latency ?
Dan