Hi Pete,
I appear to be having the same problem. I am installing FSUIPC5 (unregistered) to support TOPS Takeoff Performance System v1.2.0 use with my PMDG 777-300ER. Maybe my description of the problem will help both myself and Julian.
I have installed FSUIPC5.122 under P3D4.1 but now, when starting Win10 Pro, at the screen to enter my Win10 PIN, I receive the window "P3D requires a minimum display resolution of 1024x720. Would you like to change your display resolution? Yes/No". I am using a 4k screen with resolution 3840x2160. On answering Yes, I receive the P3D splash and a Desktop Icon Settings window. On answering Yes to this, the settings window disappears but so too does the P3D splash and P3D ends.
If I rename FSUIPC5.DLL and restart, P3D loads without a problem. Restoring the name FSUIPC5.DLL again returns to the same problem.
FSUIPC5 was run as Administrator, both the .INI and .LOG files are present, and the security tab of the Modules folder shows Full Control and Modify ticked for Everyone. I have attached the FSUIPC5.LOG file of the installation.
Can you help me solve this problem, please?
Many thanks
FSUIPC5 Install.log