first off sorry if this has been addressed already, i couldnt find another thread tho so i figured start it. second, im not sure if this is exclusive to ps3 or crosses platforms. third, my post will contain spoilers(someone needs to show how to make that cool little spoilers tab)

last night i encounted a bug during the fight with alduin at the throat of the world during alduin's bane quest in which Alduin would remain invincible even after being hit with dragonrend. after i read the elder scroll at the time wound and learned dragonrend, alduin appeared like normal and i proceeded to attack him using dragonrend. the first time everything seemed to work fine, dragonrend forced him to land and i was able to damage him accordingly, however on my first attempt i died and this is where it gets strange. when the game reloaded(from the autosave it makes after the elder scroll scene) alduin would not say his usual line of dialogue and would just fly around in a few circles before eventually engaging with parthanaax, when i would hit him with dragonrend it would force him to land but i could not do damage to him. i reloaded and tried several times from the autosave with the same effect. However, when i reloaded from a previous save before the elder scroll scene and went through the motions of reading the scroll and watching the little cut scene again everything would fire off normally and i was eventually able to defeat alduin.

so ya, hope this proves useful to someone and maybe others will chime in if they had a similar experience with this or another quest involving scripted scenes.