The Photopost Pro program does not interact with the vbulletin admin panel in any way. As suggested before vbulletin has no idea Photopost has been installed.
I would highly suggest you disable any hacks you have installed as start with a clean vbulletin and photopost and go from there to see what
vb hack might be causing your issue.
Your issue as I see it is why is vbulletin trying to run some photopost script? We dont alter
vb in any way so this can not be caused by our scripts.