Hmm... this is strange, I haven't had any problems, personally. Are you using a save from a previous version of the game? If so, the spells may be referencing the wrong resource. But, I would think that this would make all spells unusable.
Any mods?
If no for both of these, I'd say that a reinstall is your best bet. Keep us updated, the community is generally pretty helpful from what I've seen.
-LoA
