Unable to Install P3d v5HF2 Professional

[Osprey_V22]

I purchased and installed P3dv5 in April 2020, no issues worked fine out of the box.
July 2020, updated to HF1 then HF 2.
In Jul 2020, I purchased JustFlight DC3/C47 ADDon for P3v5, installed with no problem, worked fine.

In Jul 2020 after DC3/C47 install, attempted to install Xtremeprototypes LR25 ADDon and everything went wrong!

Installation was fine but P3d said it could not find scenery files then P3d attempted to load them manually but failed.
After several unsuccessful Repair attempts and complete after a clean download and reinstall attempts:
I uninstalled, deactivated and started from scratch.

P3d v5HF2 Program loads (reports successful installation) but can't see aircraft, can't change aircraft or change airports.
P3dv5 HF2 ultimately quits.
No other addons installed on this partition.

On another SSD drive I installed X-Plane 11 it runs without problems (and was there before P3d installs).

SYSTEM INFORMATION:
AsRock X99Extreme 4; Windows 10 Home 64bit; Intel i7 5820K @3.30; 128GB Ram;
GDU: Nvidia RTX 2070, 8GB, PSU 1000 Watt Antec;
OS on 250GB Samsung SSD;
X-11 on WDC 500GB;
P3Dv5HF2 on 500GB Partition of WDC 1TB HHD

3 Monitor configuration: 1 LG 4K 27"; 1 LG 4K 24" and 1 ASUS 1080P 24".

NOTE: Also I own P3d Versions 2,4. P3d v 4.5 installed on a different computer.

REQUEST: Any troubleshooting installation recommendations.

[aeronauta]

First two things to try are

Delete prepar3d.cfg (make a backup if you had made any changes to it ) P3D will create a default one on the next start

Delete your default flight (C:\Users\YOUR ID\AppData\Local\Lockheed Martin\Prepar3D v5 , 2 files Prepar3D_Default.fxml Prepar3D_Default.wx ) P3D will create a new default one.

restart P3D

Jorge

[Osprey_V22]

Jorge, thank you for your prompt reply and recommendations. After deleting p3d.cfg file and rebooting P3d wanted 10 or more scenery files deleted. I did that. On rebooting P3d is "Building database for new scenery files". It's at about 21% and looks like a long night. Just want to let you know status and will give more details tomorrow. Again, Thank You!!

[Osprey_V22]

Jorge, deleting per your recommendation didn't fix problem. P3dv5 wanted scenery files deleted, I did but some I couldn't, for example vehicles_Aircraft".bgl

Here is the error message: SCENERY.DAT file error. Close Prepar3D, and delete"scenery\global\scenery\vehicles_aircraft.

This is after having deleted prepar3d.cfg, and rebuilding all those other scenery files last night.

NOTE: NO CHANGE P3Dv5HF2 won't run, "Program Not Responding" at setup Vehicle and Location screen.

Today I'm going to uninstall P3dv5 again, including "ALL" the config files I can find, do clean download of v5 (without Hot Fixes if possible) and reinstall v5 and see what happens. For the Last Time.

If reinstall doesn't work, I'm going to deactivate P3dv4.5 installed on another computer and attempt to install v4.5 on the PC system described in my original post HERE that no longer accepts v5HF 1 and 2 to see if it will accept v4.5??

Wish me luck!

[Osprey_V22]

Jorge, I wiped out everything and started fresh. Reinstalled V5HF2 and all seems fine.
I believe deleting the program extensions may have done the trick.

Now, what will happen when I attempt to installed Xtremeprototypes LR25?

Thanks again for the help.