Do I need to worry about it at all? I’m using endObject() to delete some objects on collision with the player so I assume it’s related to that somehow.
More details would be helpful- but as far as I can tell from a quick google search, it’s because references to the object caused it to not actually be deleted. I’m not entirely sure what this entails, but I’d assume it would mostly be a performance issue as the memory would not be freed up.
@Captain Oblivion is right. this should not happen in 2.49 (it could happen a lot in 2.48), so an example blend would be helpful.
i just got the same error
blend file is attached.
seems like the and controller for the ipo is not removed.
just press the up-arrow key and collide with the cube to test (takes a few milliseconds, because the cube has a health of 2 which removes it once it reaches 0.
the second problem i got is, that unused ipos and images are not removed, when i restart the blend file, but i think they were removed in earlier versions?
demonstration of that is inside the file too, because i cant remove the junk which remains because i stripped the original file for demonstration 
anyhow, thanks for the help
greetings
manarius
edit:
should i post this to the bug tracker?
Attachments
zombieobject.blend (752 KB)
Apparently that comes from duplicated objects.
Attached to this message there is another example of zombie objects. Hey i liked this sentence, let me say again. Zombie objects. That’s cool, it’s awesome to debug zombies. Thank you.
Please notice: inside this example there is just to types of enemies: the standing one (white box one side red) and the moving one the orange box.
I inserted both of this “enemies” using the appending function. 
Yours,
Ortiz
Interesting blog post by Social, related post: http://theblendwithnoname.blogspot.com/2010/01/every-death-is-suicide.html
Attachments
AMRELEASE1RevMatrixBZombies.blend (566 KB)
A note from my side, I bumped into this ‘Zombie error’ also. After looking into it a bit better, my object (being the duplicate of a linked object from another scene) was still parented to the object in the old scene (which was not active). Removing the parent-relation solved the problem for me.
Before ending the object, you should check if it is still valid, this can be done with:
if not object.invalid:
object.endObject()
In 2.49b I had this problem because the parent of the Zombie Object was in a different layer. Logic bricks did not work while the object was a “zombie”. Moving the parent to the same layer fixed the problem.