Realtime Interrupt — James P. Hogan

Joe Corrigan awakens in a hospital to find that his life no longer exists. As director of the supersecret Oz Project, his job was to create a computerized environment virtually indistinguishable from reality. Oz failed. Now Joe, left alone to pick up the pieces of his shattered life, Joe finds himself in an unfamiliar world -- a world where nothing is quite as it should be. Now Joe must discover a terrible truth about his new world -- and figure out how to get out alive!