File Extension .PF

When a file is about to be opened, Windows uses File Extension OPF (also called Scenario File). First, Windows checks the correspondent directory to see if the file PF is linked to the application, before load the file. If it's available, it will use it to make the application load up faster. And will update every time the application is accesed. Windows also uses the File Extension OPF to store prefetch trace files, witch are stored in the prefetch directory.
This hole process needs the Windows Task Scheduler service. If it's running, it's okay and the file will be updated. If it's not, then the prefetch performance is not going to be used, so the file won't be read or updated.
To avoid issues in you System, it's recommended to clean up and delete regularly PF files and prefetch folder witch both of them can be corrupted. Also, don't forget to delete also File Extension OPF orphans that remains on the system after an Application Uninstall. You can do it manually.

Via GPS World