LaCie 500 not mounting

I have a LaCie 500 that has trouble mounting on both my eMac and iMac.

It works once in a while, with a lot of restarting and unplugging and reconnecting, but there seems to be barely any connection to the new iMac.
I can hear the drive whirring, and there is no sign of the drive when I open Disk Utility.

I tried to load the iMac with the drive connected, but the computer failed to start up. All I want to do is format the drive completely and use it again to backup the iMac.

It was previously used to back up the eMac, and it has trouble mounting even on there.

Anybody?
I hope it's not faulty, we've only had it a year or so.

Sorted.
I managed to get it to mount on the eMac again. I erased the drive, repaired permissions (which apparently didn't need repairing) and it mounted on the iMac within seconds.

About to run Time Machine for the first time.

I also have the smae problem except I cannot mount my drive at all anymore. how did you mount yours?? mines jut stopped mounting a couple of days ago.

help please, i got lots of work on that drive.