FireWire HD Problem

A few months ago I purchased a LaCIE D2 Triple Interface external hard drive. I only use it once in while for a back up. Most of the time it is disconnected. It was working fine all this time via Firewire 800. I went to use it the other day, copied a few files and turned it off. Now it will no longer mount when I turn it on via Firerwire ( 400 or 800). It works fine in the USB mode. I tried it on another Mac with the same results. In the meantime, I zeroed out the drive, disconnected the power cord from the Mac overnight, hoping to reset the firewire bus, but it still refuses to mount via firewire. I also tried several different new cables, again it will not mount. In the meantime I figured it would be worth a try to Zap the PRAM to see if this would correct the problem. Now, both computers that I had this drive connected to will no longer allow me to Zap the PRAM. Maybie it is just a coincidence, but I never had a problem in the past with either computer in the past trying to zap the PRAM. I sent off a e-mail to LaCie tech support, but haven't received a reply so far. Does anyone have any idea as to what might be going on. Thanks