Workshop -> OpenGL
Try disabling Postprocessing. Try disabling Pixel Buffer. Try upping Texture Memory to 1024.
Test each one individually.
Can you explain to me what you mean by "glitches" and what specific textures are missing (field, battle, world, spell, menu, all of the above, etc.)?
You should also post your Profile Details and your APP.log at the time you see the "glitches" and/or missing textures.