I have noticed that computers (and I assume turtles) that are already placed won't have any problems, it's just when you destroy one and put it down again that they stop working.
EVE Online characters:
Daedalus II ex-CEO TOGOA, Daedalus III slave of Daedalus II
Little Molok Asura Engineer
"Each day I don't get an attempt on my life by a robot from the future I see as a personal failure"