Please stop repeating over and over the "problem is Couatl.exe". YOU posted a screenshot clearly indicating what the problem was, and I replied to THAT, and that was undoubtedly a problem in the VC++ 2005 redistributable.
Now you are saying you changed the TEMP folder, which clearly indicates my suggestion was correct, so it works now ? If yes, let's go to the next step:
To open Prepar3d v4.5, a blue GSX scenario update bar and logo or P3D go into the background indefinitely. We have waited more than 1 hour and have not proceeded to the P3D splash screen. When the task is finished, the Windows task manager accuses or crash coualt.exe
Your mistake here, is to continue to assume Couatl.exe is the "cause" of the problem. The simulator is crashed, and when it does, it MAKES Couatl.exe to crash. You call yourself a "Systems Analyst, please don't tell me you don't know that an .EXE started from another process CANNOT crash its parent process.
If you read the other thread in the forum, the problem you are now reporting, which doesn't have *ANYTHING* to do with Couatl, which is the simulator locked up on start, was instead caused by the Addon Manager, which for some reason is SOME 3rd party sceneries were installed into a path with non-ASCII characters, made the Addon Manager crash. The Addon Manager is a .DLL so, opposite to Couatl, it CAN crash the sim.
Of course, as you can see in the relevant thread, the problem has been solved, and the updated .DLL is online now.