You fail to mention which operating system you are using.  If you are running Vista, Win7/8, the correct runtime to use will be my libraries/documents/poser10.  In those aforementioned OS's, User Access Control (UAC) will interfere with any content placed into Program Files folder.  Better still, you should organize your content and create external runtimes for each category or figure you own.  These external runtimes can be located anywhere as long as they are not placed into Program Files.  

PZ3's are scene files; those can be placed anywhere.  I find it strange that you are placing them into a Python Script folder.