The TrackIR.exe appears in the Task Manager process list.
I have uninstalled & reinstalled the the latest and previous versions of the TrackIR software.
I have run the NP Registry fix on the off chance, without success.
With the latest 4.x software on a laptop the TrackIR worked fine, so it's unlikely to be a hardware problem.
Any assistance at this stage would be greatly appreciated as I don't enjoy using FSX without head tracking and I have not flown since the problem started.

Regards, Jr.