You should also consider your behavior before and after the attacks. This happened to me with Noah for the first month...the reason was is that I was jumping around sreaming each time he attacked. It was FUN to have a giant squeek toy to play with!
We noticed this kind of thing so running, sqealing and other exited behaviour is avoided when he's around. He attacks when I'm sitting quietly, coming out of nowhere, and is perfectly calm before he bites.

Before you consider diagnosing this cat with mental problems, see how things go when you calmly react to his atacks by placing him on the floor, with a toy, away from you. If he continues, use a spray bottle.
Of course me must have one of the only cats in existance that doesn't mind getting wet!! He'll sit there and let us soak his furr and just look at us. The only time he bothers to walk away is when we spray him directly in the face.

Good luck and let us know what happens with Scooby.
Thanks for the ideas! I'll keep you up to date!