I believe that if you delete an old package file from a currently working PS, that PS will most likely experince the issue that the new PS is having.
I think it may be due to the NSOwnerGuid no longer being correct for the old packages.
It may also be worth reviewing the 7.1.2 MP1.1 v7RU Release Notes to see if any of the RU's have addressed this type of issue, as I do know that a number of PS related issues have been fixed by certain RU's.