Malfunctioning Yaw in FSX

[Benalar]

Hi everyone!

I have a serious problem with my TrackIR5 in FSX.
I bought it a few weeks back, and everything seemed to work perfectly at first. The software worked great, and I used the TrackIR in DCS: BlackShark, no problems at all. But then I tried it in FSX and the view gets really messed up here. The yaw-axis keeps centering on some point to the left, then jumps back to where it's supposed to be when I move my head. Sometimes it works fine for a few seconds, then it jumps to the left, stays centered for a few seconds, reverts back again, etc.
At some point I thought I fixed the problem by starting the TIR software after FSX, that worked for a few hours. But now the same problem appears again, so that wasn't it.

Again, the TIR software works fine; even when the view in FSX is jumping, the software shows it tracks the correct movement. So I guess it has to be some FSX-related issue.
Any help would be appreciated, thanks in advance.

[Benalar]

I couldn't find an edit-function..

Here's some more info:

It doesn't work with TrackClip either.
The TrackIR is plugged in directly to the PC.
I have both Service-Packs for FSX. The only addons I use are FSPassenger and Active Sky Evolution. The problem still appears when I start a free flight without ASE and FSP.

System:
ATI Radeon HD 4850
AMD Phenom 9550 Quad-Core Processor, 2.20GHz
4GB RAM
Windows 7 professional, 32bit

[VincentG]

Looking at the TrackIR software, camera view, what do you see here?

Any red/gray within the camera view?

[Benalar]

Camera view looks fine, just three green dots, nothing red or gray.

I believe the problem is somehow related to my Saitek X52. I tried plugging it out before starting FSX and TrackIR, and the problem hasn't occured again.
However I'm still not sure, because I can't reproduce the problem, but as long as it works now..