Umberto, I think that the message was due to the fact that I had to close FSX through Task Manager because (only after having flown to KDEN) it hangs on without closing.
The addons I have installed are too many to be listed. Many Aerosoft, FlyTampa, FSDT, FlightBeam, Orbx, ImagineSim sceneries. UTX, GEX, REX and many Aircraft like PMDG, Majestic, Carenado, A2A, Aerosoft, LeonardoSH...
The doubt I am having now is that i moved and connected through "Junction Link Magic" three folders to a second local drive. They are: Addon Scenery, Aerosoft and Real Environment Xtreme 2.0. Could be a problem? Would be strange then because with all other FSDT and FlightBeam addons I don't have any issue.
Thank you one more time for your help.