Help required with a dll error!

Hi all,Im having a serious problem with FS2004 keeps crash on loading a flight at around the 80% mark or when I'm flying.This is a random time error but always happens!The Microsoft error is:-AppName: fs9.exe AppVer: 9.0.0.30612 Mod: ntdll.dllModVer: 5.1.2600.2180 Offset: 000106c3I tried to Google the error, no joy.I tried replacing the ntdll.dll, no joyPlease can anybody help me?????Dave