Thanks Sven, I did check that he was not copying reports. I also had him copied over to a test user. I can't recreate it, even logged on as him. I doubt it's in a BADI as it is only one user this is affecting. I'm certain it has to be something unique to his user ID.
I will sit with him for his next report and see if anything jumps out at me.
I'm open to any other suggestions you might have.