I installed the 2 dll files from the hotfix and the project manger cannot find the xml files and fails to load the drawings in the projects.
I created a new project and the same thing happened.
Tried to repair and reinstall P3D 2013 and this did not fix it.
Finally copied the original dll's back to the P3D directory and it is working again.
The 2 files are PnIDProjectPartsMgd.dll and PnPProjectManagerUI.dll
This issue has come up on occassion when using the ZIP extraction built into the Windows operating system.
Please extract the files using a third party utility such as WinZIP, 7-Zip, etc. and try replacing the DLLs again.