"Soft" clicking can be caused by a variety of factors. If you believe this is the type of sound your product is making the problem is almost always related to the amount of power that the device is receiving.
For devices that receive their power from a USB or Firewire cable, you may need to either switch to using a power supply (if you don't have one, LaCie can provide one) or adding a second power cable via either a power sharing cable or power Y-cable. Most of our mobile products ship with these cables included in the box already.
Other issues that can cause clicking, although less often, are severe data corruption or faulty communication cables. If replacing the power supply or power cables did not solve the issue; try replacing as many components as possible with known-working pieces - including the computer.
What is the situation you are facing?