Problem with LaCie 500 GB d2 Quandraq

what os do you have

http://www.pricespider.com/products/454765/LaCie-D2-301110U.html
This link has product reviews and problems others have had with it. It may be worth checking out.
Let me know how it goes,
Thanks
yalmer

Hello,
if the unit has the original hard drives inside (i never one with 10 000 rpm drives though), the problem might be caused by a power issue.
Please verify the power supply by plugging it into the wall then listening to it. It should be silent. If there is a high pitch noise or hissing, it is defective and needs to be replaced.
If replacing the defective power supply did not solve your issue or if the power supply did not have any issue at all, the internal components will need to be inspected.
If you replaced the internal drives with 10 000 RPM drives, it might be why the drives do not get enough power.
Regards,

Try pluging the device to another Pc to see if the device works

am not so sure if this is a similar issue with iomega external drive in which the drive wont show up on My Computer but when the external drive was plugged into an ubuntu machine the drive was being detected and working just fine.

Please try to do the same. plug your external drive to an ubuntu machine and lets see if it can be detected. If it is then the hard disk has a similar issue with iomega drives. check this link for the solution.

Same here. I pulled the drive from the case and swapped it with another and the drive works fine. Must be the control board inside the case. Where can we find the replacement board?

This is most probably a faulty power cable, a common fault on La Cie apparently. Another cable got my disk working fine! 

i'm not sure i can solve this problem--which started for me tonight as well with my lacie d2 quadra 500 gb--but i can share a possible explanation i've found online: apparently, they have lots of problems with their power supplies. see if the power adapter (the black brick) is making a hissing sound, or if there is a ticking sound coming from the drive itself. i have both these sounds. i am hoping all my data is safe and that my i.t dept. will be able to fix it with a new power supply on monday.

Listen to your power supply and see if it is making a faint buzzing noise. Try your device with a new power supply. With a new power supply my drive now runs fine, and was not corrupted.

Maybe the usb chip in the hard drive enclosure that converts ide into usb failed. You could replace the enclosure (they sell enclosures at best buy) but it could be quite a hassle.