The bug with the bow (The Elder Scrolls 5: Skyrim)

Play this in Skurov, everything is fine. At a certain point, run up to the dragon to shoot a bow, and then BAM the game freezes and the sound goes. Well I backed up right before the fight.
Start again. BAM - again hangs. And so each time until I thought of a dragon plugging sharpening. Around the MAG, then back to the bow moved, preserved. Play, play, everything is fine. And suddenly again when firing it. Reinstalled the game, already downloaded from another site, the Internet sought out the cause of the problem. Nothing helped! On the minimal salary is already set(although the computer pulls the game on ultra perfectly): nothing has changed! Play the pirates, mods do not have, but the client went with three add-ons.
What to do, Lord?