Morrowind - Seyda Neen Invisible
A strange glitch in the game. When I returned to Seyda Neen for the Mal Bolagmar quests I found it completely missing... That is, all except for the lighthouse. So I went into the lighthouse, and when I came back out, all the interactable elements (doors, containers, and NPC's) were back, but nothing else... weird.
I forgot to check, but I bet the hatch to get in the boat was still there too.
And sorry about the music... it was my brother's idea. I couldn't think of anything.