Critical error #001 when install

[Joeflyer]

Dental, it's not always a good idea to apply a hotfix to P3D. Many users have issues with doing this. I have always found it better to do a complete
uninstall and re-install of P3D 2.5 (the last version of 2.5 installer had the hotfix included). It alleviates most problems. If you can't do this, it
might be a good idea to delete the shader cache in the LM local folder for P3D 2.5.
You didn't mention what problems you were having with FsP after applying the hotfix anyway.