I've got two.
1: Last time I was at Universal (2004), my family went to Mardi Gras at US. After watching the parade and feeling 20 pounds heavier because of the beads, my brother and I went on to E.T. So far no problems. Near the end, where you see E.T.'s homeworld with the aliens, our "bike" got stuck for about 15 (or 20?) minutes. First, the animatronics stopped talking. Then, the music stopped playing. To finish it off, a girl of about 16-18 dropped her cell phone. My brother and I tried to help, and it almost fell off the vehicle!
2: In Disney's less modern version (Peter Pan's Flight-notice how two similar ride systems were both broken down?!), my brother and I (again) got stuck for about twenty seconds right outside the very first scene (Wendy's room). That Wendy animatronic is both outdated AND creepy!