All of a sudden, all of my instruments that display heading, including the compass, show an incorrect heading. Depending on where I am, it may be off by as much as 30 degrees.I know about the "D" key -- it is not gyro drift. It is not magnetic variation, because we are talking about 30 degrees here at airports where it may be 2-5 degrees. It is so bad that Radar Contact ATC keeps giving me devil for drifting off my assigned heading.I did a search here and it appears that it might be a scenery bgl file from a recent install. However, I have deactivated every add-on scenery back to the original basic MS FS9 install and moved the folders out of FS9. Yet, still I get the heading error.I also used ScanAFD to see if there were any obvious problems. Nothing was found.Anybody got any suggestions of other things I can try?Thanks in advance for any help,Wilson

Usually a scenery will cause this what were the last couple of things you installed?

Randy,Thanks for the reply. Yes, I figure that it must be a recent scenery installation.But, as I said, I have uninstalled every add-on scenery and am still having the problem. The last scenery installed (and only recent one) was KRDU2010. I removed it from the scenery library menu and then removed it completely from the additional scenery folder.One odd thing that I noticed. I deleted the FS9.cfg file and let it rebuild. When I go to any runway after a rebuild, it is correct. But if I then go to another airport, the problem returns. There are time when the error is as much as 110 degrees.Still no luck.Wilson