Pretty much anything (cabbages anyone?) that has to load up when you reenter an area. Could this be the culprit? I remember destroying the two skeletons to the west of Whiterun and this is the place where it seems to skip frame (worst case-scenario being a crash afterwards). Their bone pieces always fly and roll all over the place. I remember hearing bones but I couldn't see anything. Could the physics be wonky for this? I never see an answer for this issue. Could be due to the dragon that never fought me and flew off?