My FS2004 runs fine but it does have a little quirk. A while back I installed scenery called FlyTampa-Maarten. The scenery looks great, but the problem arises when I install additional scenery; FlyTampa-Maarten will be listed twice in the add-on scenery Areas List! I then found a work around by removing both FlyTampa-Maarten's in the Areas List. Next time FS2004 is launched there will only be one FlyTampa-Maarten listed. Kind of a hassle to go though that though.
I looked at the Scenery.cfg file and after some searching and digging I found two Layer=85 instances. One is from FlyTampa-Maarten and the other goes to US Roads - West (Major Only). See graphics. Maybe since both have Layer=85 that is causing FlyTampa-Maarten to be listed twice after another scenery is added?? Thanks! Andy