WTH?

[BeckerCheez]

I go into a house I usually play on my rotation, and the teenaged daughter is transparent.  I do a force error and she disappears from the game (ie her pic in the panel is gone).  So I move the family out and back in.  She's gone!  Yet she shows up in the family portrait on loading...but I can't move her to Uni!  Is she a lost cause?  I don't know WTH happened to her and I'm not sure what I would've done!  :S

Edit:  I check the family tree and she shows up as dead. Wha!?

Edit 2:  now I'm checking to see if she's ressurectable.  If she did happen to die, why on Earth did the game not flag it with "Your Sim has died on another lot" instead of freaking me out with her appearing as a ghost?   

Edit 3:  I"m such a dumbass.  She got eaten by her friend's grandfather's cowplant!     It still doesn't explain this phenomena though.

[Marhis]

I've seen a similar thing when I gave a sim the death token via debug menu: the next time I loaded its lot, it appearerd ghostly but apparently behaving like a normal sim, and disappeared after a while.
The same happened when (in base game) Don Lotario died while visiting Caliente's lot: when I load Don's lot, he was there, transparent. He chatted a bit on the computer then disappeared, this time with the message.

Maybe a random glitch.