I have been working on a secert test  

 base in Alaska and recently encountered a problem.  I have been modifying the AFCAD and adding scenery to Delta Junction/Ft Greeley [Allen AAF], AK, US (PABI).  Everything was going fine until the other night.  When I started up FS2004 I went in and selected a flight starting at PABI.  When I hit "Fly Now" the FS2004 spalsh screen comes up, then after 5 sec FS2004 quits and I am back to the desktop.  
I then decided to start a flight at PAED and fly up to PABI.  Everything went well until I was about 10 miles from the PABI when then again FS2004 quits and I am back to the desktop.  
So I am stumped.  I have removed all of the modifications I have made and went back to the default scenery and AFCAD but still No Joy.  
Anyone have any ideas?
Thanks in advance.