something very similar actually happend to me onny my sim had just gotten on the bus but it wouldnt move or days. there was nothing in front of it but it still wouldnt move all it would to was sitt there and honk. after a few day the bus finally drove off but the sound of the bus kept going for a few more days after that. that bus had lots of glitches. but all i could do it wait it out and hope that it went away, and it did, but it was still annoying.