Permission suddenly changed when trying to edit!?

Hi there!

I have a little issue with one of my objects, an earring in particular. Within the inventory, the permissions are set to copy/mod/notrans, same in the properties window. Next owner permissions are set the same. Within the object, there is one linked prim containing a script that is copy/nomod/notrans.

What I am trying to do is a) remove the script and b) extend the object by linking some other prims to it. But when I rez the object onto the ground, the edit window suddenly tells me I'm not allowed to modify, so I'm not able to remove the script or link other prims to it either. Evenmore, when I take the rezzed object back into inventory, it's permission is suddenly changed to nocopy/nomod/notrans!

Question: Why am I suddenly not allowed anymore to edit the object and what can I do to prevent loosing the obviously granted modify permission?

Thanks for your help, Ansariel

Edit: It is not an object I created myself but a freebie I got some time ago.

I had a similar thing happen a couple of weeks ago when I was making something and ended up having to rebuild the item from scratch. Assume the item is totally borked at the asset server level now, so either live with it as is or delete it. If you remember where you got it from you can always go back and get another.