I've seen this happen a couple times. There are a lot of Sims sharing the instruments (piano, guitar, violin, child-sized violin) in the household. With the instruments the Sims pick up (guitar, violin, child-sized violin), they put them down in random places when they're done, rather than putting them back where they got them (where they belong).
Sometimes, a Sim will put down an instrument so that it is facing a wall (or other large object, like the piano). When other Sims try to play the instrument that is facing the wall, they throw up their hands and cancel the action. I have to turn the instrument around so that it is facing a direction the Sims can approach from, and then they can play it again.
It seems odd to me that a Sim will put down an instrument in an orientation, but cannot then pick up the instrument that is in the same orientation.
I'm playing a pretty vanilla game with no packs, mods, or cc. (I did have a mod installed, but an update disabled it, and to help track another bug, I followed the EA-provided instructions for clearing it, resetting and repairing everything, and then resuming the game.
