I had this problem the other day. For some reason, the P3D root folder will open upon P3D launch if you have a faulty addon.xml in your doc's folder, or a addon.xml pointing to a non existent or faulty addon. 

In my case, I had to remove all my xml from my doc folder and go through them one by one until I found the culprit. 

Hope this helps. 

How do I know 

On 21/01/2021 at 5:36 PM, SolRayz said:

I had this problem the other day. For some reason, the P3D root folder will open upon P3D launch if you have a faulty addon.xml in your doc's folder, or a addon.xml pointing to a non existent or faulty addon. 

In my case, I had to remove all my xml from my doc folder and go through them one by one until I found the culprit. 

Hope this helps. 

How do I know which addon.xml in pointing to a non existent addon? 

I'm looking at the XMLs in the root folder and I can't understand where they direct to?

1 hour ago, Mattie941 said:

How do I know 

How do I know which addon.xml in pointing to a non existent addon? 

I'm looking at the XMLs in the root folder and I can't understand where they direct to?

No, no, no... The problem is with one of the add-ons in your documents\Prepar3D v5 Add-ons\ folder.

Inside of that folder, you will see a folder for each add-on. Make a folder on your desktop and move half of the folders in documents\Prepar3D v5 Add-ons\ to it. Then, try to start P3D. If the explorer window still opens, the problem is in one of the add-ons still in documents\Prepar3D v5 Add-ons\. Quit P3D, put the ones you just moved to the desktop folder back in documents\Prepar3D v5 Add-ons\, and move the ones you left there to the folder on your desktop. Try to start P3D it should start this time. If it does, move the folders back a couple at a time until you find the bad one.