For some reason, some graphics (armor, walls, etc) are just shown as blue blobs in the shape of the item. Does anyone have any idea what might cause this?

Could be a mod ???

That sounds like a mesh problem. Are you using texture/mesh mods? If not, you might want to try a game cache verify.

Check your load order. I had this happen once with Aela's bow, which had turned light purple, and a quick change in load order fixed it right away.