What does Stephen's laptop represent in the novel, Disclaimer?

Stephen's laptop represents his disconnect from reality and decent into his mental illness, focused on torturing Catharine and her family.

Prior to the laptop Stephen was filling his time with writing, attempting to write a non-fiction book. With the laptop he has abandoned his book idea and become dependent on the internet for food, news, supplies, and anything else he might need. At the end of the novel he gets rid of the laptop, representing his acceptance of his laptop's role in his misdeeds.