I forgot to say, yes Semantic/Pragmatic Disorder is typical of being on the spectrum and is one of the Disorders that a good Speech and Language Therapist will tell you that you are looking at a probable diagnosis of autism.
It is also called Semantic/Pragmatic Disorder. Have a look at http:// www.hyperlexia. org/sp1.html. (take out the spaces).
This gives a long explanation and good examples of it.
My son also has this.
But I am wondering what is the 'cause of it'. There is the Autism (my son is diagnosed as being on the spectrum), then there can be Auditory Processing Disorder (my son is now being assessed for that), and Sensory Integration Disorder (my son has that), and Echolalia (my son has that).
All these Disorders have similar charteristics in them and it maybe that it is just rather like a fruit salad of aspects of other Disorders which manifests itself in speech and is called Semantic Pragmatic Disorder.