For many years I have been flying the PSS B777, however having not flown it recently, so I thought it was about time a added a few more flying hours.However having tried to get FS2004 to run again , I encountered problems. So I have ended up reloading FS2004 & PSS B777. Still on an XP platform. I have also added the two B777 patches v2 & v2.1.Whilst it runs, the autopilot is very unstable with it constantly oscillating, mainly on the height but also on headings. It would appear the the system is constantly altering the stabilizers. As such the height rate of change keeps changing from about -800ft/min to +800 ft/ min with the height constantly 'going through' the target height.I have checked the version of Direct x and it is the latest (9.0c). The video card I am using is a dual screen matrox G550 (but set to single screen mode).Can someone please provide some assistance, as I would love to fly my B777 again. ThanksSignalmanP.S Autoloands are interesting with this problem and are more like autocrashes !! :(

Did you install FSUIPC?

'Porpoising' can be an issue in some FDEs. In the aircraft.cfg, look for a section called [flight_tuning]. One of the lines in it is:pitch_stability=1.0which is its default value. Increase this gradually in increments of say 0.2 until the porpoising stops - it's infinitely easier than re-writing the FDE!If your. cfg file hasn't got this section (not all do), just add the title and the line as indicated.;)