We do not DO anything to get it to happen, it just happens every once in a while when a new user registers. To date, I cannot find anything similar amongst the users that this happens to. They come from different IP ranges, different email services and all types of user names.
Is there something they could enter into the registration (i.e. password) that would be valid for
VB but not for PP?
It seems to happen during registration somewhere along the line, I assume whenever they are added to the PP user database.