Thanks for eliminating SDK and FSUIPC4 as something that might affect the throttle quadrant. I'm trying to again retrace everything I've done re FSX installation. I installed FSX Gold package and then Traffic 360. My recollection is that I then flew FS simulations with no problem. Some days later I installed SDK & sp1A, FSUIPC, and an airport editor called ADE 150. In retrospect I can't be sure in what order I installed those programs. Looking again at the ADE 150 documentation it mentions that it works with both FS9 and FSX. Having eliminated SDK and FSUIPC as suspects, I'll concentrate on ADE 150. Windows control panel doesn't list ADE 150 as a program to be removed, so I'll try to find and remove any ADE 150 files before starting over to build an FSX suite.
After many years of using FS9 and add-on's (including FSUIPC), FSX has been extremely vexing - due to my own lack of knowledge and understanding I'm sure. This is my third try at FSX. Twice before I gave up and it was probably a couple years between each before trying to install it again. I'd appreciate your comment on the best sequence for installing the following: FSX, the SDK and SDK service pack, FSUIPC4, FSX enhancement programs for AFCAD and scenery design, Traffic 360, traffic modifying programs, add-on aircraft. (I think I'll keep a log of the next installation sequence.) Your help has been much appreciated.