You can not import users into
vb and use photopost scan database to fix things that will make it worse and there is no way out of that. You need to restore a backup of your photopost photos table and run the userfix script noted in many threads on switch integration. The product is not designed to switch an integration so we need to try and counter what we can.
Switching from phpbb to vbulletin
There is only so much we can do to counter issues with other software when you switch integrations
Reassign userid's when switching integrations to VBulletin