My Porsche Lacie 160GB disk

Question

My Porsche Lacie 160GB disk no longer mounts on my Mac OS X. OS is fully up to date at 10.5.6. I've tried it with different firewire cables and on multiple Macs. One is a dual G4 desktop, the other is a MacBook laptop 2GHz Intel Core 2 Duo. I have never had a problem with the drive...The drive does not show up in Disk Utility...Thanks!