Sigh . . . count to 20 . . . leave your computer.
Is the client procrastinating or are they just short staffed and overwhelmed? Or perhaps they are waiting for some key information which you need. Is the deadline you both agreed upon when you first talked about the job still realistic? By talking to your client you will have a better understanding of what's causing the procrastination and perhaps create a positive solution, or some alternatives, that help both of you.