The matter is What did you add to fs9 folder after this??
it seems like a texture loosing bitmaps or in fs9/scenery/World/scenery and a *.BLG has missed to me,try to restore the most recenly point before that,..If you using win xp((i hope you know hw to do it ,if you don't try someone's help who know to deal with it),It may set back again,the things you lost,i mean A *.BLG or texture bitmaps....do it and tell me
Trust me buddy! RESTORE! is so simple you won't have to search a cd or anything just set your computer to a moment before this issue,It won't do nothing bad and if I mean,.. IF.,, (never seen since XP came out to the market)somethings goes wrong(you may be need and exorsism

because it will be real strange))You just simple disable the restore........

."Disable"

I realy don't know how it call in xp english version,In spanish is DESASER RESTAURACION I s an option very simple and easy,..you wanna do it the hard way reinstal FS-9 or seach the *.bgl missing wich i would consider a tidious option