TIR4 keeps losing signal

[redamedus]

My new TIR4 (s/n xxxxx) seems to keep losing the signal from the TrackClip in FSX. Whenever I keep my head still (TrackClip is not moving) when i'm concentrating on the flight instruments, after a few seconds TIR loses the Trackclip signal and centers the view and the green top-led goes dark. When I (very slightly) move my head again it turns back green again and goes to its former position (usually slighty downwards, looking at the flight instruments). TIR seems to only keep working as long as I keep moving the TrackClip.
I tried switching from a motherboard USB plug to a (separately powered) USB-hub but there is no difference between them (both have powersave turned off).
I have an Asus P5Q3 Deluxe motherboard with Vista Home Premium SP1, FSX SP1 with Acceleration Pack, TIR software 4.1 build 36. All drivers are up to date and software is (afaik)set up properly. Can anyone please help?

[VincentG]

Looking at the tracking screen, what do you see here?

How far away is the camera placed?

[redamedus]

The tracking screen shows three green dots, nothing else.

The camera is about 3 feet away and about 8 inches higher than my TrackClip.

[VincentG]

And moving your head doesn't loose track of the clip, or any of the objects turn red?

[redamedus]

No, in the tracking window everything works fine, the problem seems to be only in FSX.

[VincentG]

Any firewall/antivirus software running?

Running both as an admin?

[redamedus]

TIR and FSX were already running as admin, but my desktop shortcut to TIR was not, I changed the shortcut itself to run as admin as well and that seems to have fixed the problem. I should mention that I also turned off Light Filtering in the Tracking screen and changed the screen resolution of my desktop and FSX to a higher value, but my guess is that the shortcut running as admin did the trick.
Anyway, thanks for the help!