ai.player.dll
The ai.player.dll as far as I know in FSX has to do with your AI Traffic.It was a few versions ago that I last tried it so I just tried it again in 2.5 just to be sure but no joy.
I even aliased both the panel and sounds to the FSX C172 but that didn't fix it.
I get an appcrash popup that says Prepar3D.exe has stopped working and that the fault module name is ai_player.dll if that means any thing to anyone.