Phil,IIRC I have seen some users getting rid of this problem uninstalling the 747X making sure all PMDG related stuff are removed. If not manually delete any remnants and then reinstall the 747X. Again from the top of my head it seems sometimes the installation goes bad.It might be worth a try before reinstalling the whole shebang.Hope it helps,

Already done that. Even scanned and removed from registry.

Dude, take a default FSX plane and set it on the end of any runway, startup the aircraft and throttle forward a few feet. Check the default FSX GPS and see if the heading on the compass matches your display in the FSX GPS, if it's off by 30 degrees or so, then you have a bad AFCAD. Save the flight to restart quickly later in this trouble-shooting procedure.Then check your FSXScenery AddonScenery folder and your FSXSceneryGenericScenery folder for AFCAD files. Move, not copy, all of these AFCADs to a temporary folder location (outside the FSX path) keeping track of their respective original folder locations. Now disable any add-on sceneries in the FSX scenery library by unchecking the respective checkboxes. If you not sure what to disable, check the path and under the respective scnery folder, look for any AFCAD files, if you find one, disable that scenery.Now fire FSX backup and reload the saved situation file used before. Don't forget, you have to move several feet for the default FSX GPS to correctly orient itself. No check the compass and GPS, do they agree? If so, you have a bad AFCAD file. If not, you more than likely have a bad magnetic bgl file. For the later, get the file from someone by e-mail or get off the original FSX media. For a bad AFCAD, start renabling sceneries and recheck the issue by loading the situation file again, comparing the compass and GPS. If all sceneries turn back on and alignment is still good, then start copying back AFCADS to to their original locations. Do about half the files at a time (half-split trouble-shooting) and recheck. Problem re-appears, then once-again romove some of the AFCADS you just restored, and so on. This method only takes a few minutes to find the single bad AFCAD file and I've been successful in finding a single bad file out of 4000 AFCADS in my FS9 collection.Good luck.

Hi AlMany, many thanks for the detailed help. All PMDG had to offer via email was to COMPLETELY remove my FSX installation and start again! Finally, reluctantly, i've just done this (at lease itmeant i could do a clean SP2 install).Nada, nothing, zilch, no change! I now just have an FSX install with ONLY the 744 and it still does it!!! Bah humbug i say!Will still try as you say just out of curiosity.Ta!EDIT: Yes PMDG, I DID remove ALL other FSX related files.

No such luck!HOWEVER.... I just installed FSX again (!!!), followed by only the 744.This time however, i did not install any additional liveries, and have just completed a short route with no probs. That i do not understand. Anyone else?

Maybe redownload a few liveries fresh from PMDG and try those and see if the problem reappears? If it doesn't download the rest and reinstll all of them and check again?My two cents worth... Really strange as I haven't seen this exact problem before and I've seen most of the common culprit issues...Other than that, maybe hard-drive issues, bad sector where the magdef bgl file is getting laid down on the drive?I would trouble-shoot with FSX and SP1 only though... All the experts haven't nailed SP2 yet and SP1 seems pretty stable...

Thanks Al, apreciated.'tis truely bizarre to say the least. Apparently, PMDG have "five" other people with the same issue, so it's not a completely isolated case.Ho, hum.... story of my life;-)

Is the FSX default aircraft offtrack as well? If they are, then I think it's a FSX issue. If not, then a PMDG / Navdata issue. When you last re-installed without the liveries, and it seemed to be fixed, had you updated the Navdata yet? What cycle does your init-page in the FMC indicate, both when it was off-track a now, on-track?Just a few more thoughts...Also, I see you're running Vista. Where do you have FSX installed? It's not under C:Program Files is it? That has been causing priveledge/write problems, even with UAC turned off. Are you installing and executing FSX with UAC turned off and righ-clicking the installers and choosing "run as admin"?But, I still stand by my original theory. Heck, I saw this exact same thing a few weeks ago with FSX-Accel/SP2 and the PMDG-744X. I reinstalled FSX from the ground up since then, and haven't seen it since. The one thing I haven't done yet, is re-install all my third-party sceneries or downloaded AFCAD files. Every time I have seen this problem, it has been AFCAD related. Maybe some edited AFCAD files don't like the FSX SP2 upgrade, as I am now only running SP1.

sounds like you have the same problems as these guys?http://forums.avsim.net/dcboard.php?az=sho...id=139639&page=