If one developer tries to open a project from module files created by another
developer who uses a different path for the user.properties.file, you cannot
open the project unless you delete the private/platform-private.properties file
or change its path (if the module author forgot to delete it manually).
The "Open Project" dialog simply will not work; there's no way to open the project.

This happens even if the platform.properties file contains
nbplatform.active=default so it uses the "default" NB platform. 

I can provide a module zip file from one of Geertjan's earlier tutorials (before
he started deleting the private/platform-private.properties file manually) if
you need something to reproduce this, but I assume it would be a waste of
attachment space.