This is weirdly occurring in my game right now, but not to a sim I'm playing.  My sim went to visit the juice bar in town after work one night and found Tom Shallow standing at a fusball table, zombie-like, staring straight ahead, with his arms diagonally out from his sides.  She tried to interact with him but he didn't respond, so she eventually turned to one of the other folks in the bar who were milling about or dancing.  Later on, since she'd tried to interact with him evidently, she knew him enough to have him in her phone book.  I left her cooking, and zoomed across town to the juice bar and found him inside still in the same place with his arms raised.  I remotely had my sim call him to chat, but when he "answered" he told her he was just going somewhere and to call him later.

Every once in a while after that I would go monitor him while I had her give him a call but he always had some excuse to not have a conversation, saying it was too late, or he was at work, or he was just leaving, while really he was standing there all zombified.  From time to time as well, as I'd be scrolling over the town, I'd notice his thumbnail image at his house as listing him inside, but every time I'd check the juice bar, there he was, frozen.  With so little contact he's eventually disappeared from my sim's phone book, so I haven't  been able to call him for a while, but he never moves, doesn't blink when I set all the lights in the juice bar to hellscape-red, and eternally has his arms slightly raised, as if silently defining his personal safety circle.  Maybe someday I'll try resetting him.