I had the same problem : my aircraft compass was displaying true heading instead of magnetic heading - and navigations had become a nightmare !It took me just a few hours to identify the culprit on my system (Fs2004) : an AFCAD file for Fès Airport (GMFF, Morocco), by Ian Audisio, downloaded at flightsim(dot)com.The zip file is named "af2_gmff.zip".The AFCAD file itself (AF2_GMFF.bgl) is dated 12th June 2009 and weighs 20.0 ko. Remove it and you should be cleared for easier Navs.All other AFCADs created by Ian Audisio work fine by me.Hope this helps.