I can still remember the minute I shut mine down. I don't remember all the details of what prompted it, but just a few days shy of the board's 10th anniversary, I got up from my desk and started shutting down computers (12 of them) and then the fileserver. Didn't even "down" it. Just turned off the switch.
I wanted a full decade. I didn't shut it down right away. At 00:30 I changed it to "No logins", so no matter what name they put, it just said goodbye and disconnected. Then the next day I turned it off. The Net finally had me. I was sucked into the Matrix for good.