I really can not comment without a whole bunch more info.
I can tell you if the application is installed correctly it will work fine.
Are you not the guy who had the application incorrectly installed as a standalone instead of integrated with your forum?
If so I beleive I suggested you delete the pp_usergroups table before you reinstall to make sure usergroups are right.
I would suspect this was not done and your groups are not aligned correctly in your usergroup manager in photopost versus what they really are in your forum.
If your integrated with vbulletin forum then in your pp_usergroups table in the database you can delete all usergroups except groupid 6 which is the admin group. You can then in your gallery admin edit usergroups reimport the usergroups and set permissions and then under edit categories reset permissions.