I wanted to report that I contacted Just Flight with regard to Traffic 360 and it turned out that was what was causing my Dobbins AFB problem. The resolution was as follows: I disabled Traffic 360 in the FSX Scenery Library and successfully tested and found the problem solved. Then I went into the FSX folder to JustFlight\Traffic360\AirportFacilities\scenery\ and removed the Dobbins file (AFX_KMGE.bgl) and re-enabled Traffic 360 in the FSX Scenery Library. Everything works fine now.
I appreciate the input from everyone and especially from Just Flight who responded quickly and helpfully within a day!
Thanks,
Ken Jones