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
"Trying is the first step towards failiure" - Homer Simpson