I cleared Darkmoor Castle and picked up Memory Crystal Delta before it was an active quest.
Then, when I finally got into the Oracle I placed the crystal on its pedestal BEFORE talking to the Oracle and being given the quest.
Now the quest log is still showing the retrieval of the Delta Crystal as an outstanding quest, even though the thing's on the pedestal. It's not in Darkmoor Castle (I went back and checked). I can't remove it from the pedestal. I even tried talking to the Oracle in Castle Ironfist to check whether I had "lost it", but that didn't work either.
So...did I put my foot in it? Is the game now broken? Or will things sort themselves out once I get the other crystals?