Object linked to particle system when it should not be.

Hi I have an object(tombstone) linked from another file. Originally I was going to use a particle system to place copies in my scene. Later I decided against that Idea and placed copies of the object in my scene manually.

I removed that particle system and created others for plants and stuff. Things were going ok till I needed to create another scene using full copy. In the new scene I removed several things that I no longer needed and in the process I discovered that my tombstone objects were no longer rendering.

After a bit of trouble shooting I discovered that removing a certain particle system caused my problem…even though the particle system was not using the tombstone object. As I recreated the missing particle system I found that my tombstone object would only render if my particle system was using a certain vertex group for its density.

Does anyone have an idea how I can separate my object from the particle system so it will render normally?

Press space, Make duplicates real.

Thanks. I will try that next time. I have already removed the group, cleared everything and linked it back. Now everything is working although it was a pain.