My Skyrim freezes randomly when either I or a dragon use the Fire Breath or Frost Breath shout. It doesn't happen regularly, which means that I can use both shouts, but the game sometimes suddenly freezes. This also happens when I use the Fireball spell, but also randomly. Can anyone help me?

Are you using Deadly Spell Impacts? If so, remove it and continue testing. If not, try and limit the usage of other mods that are intensive on physical ram and/or video ram.