The fact that more than one computer does not recognise the presence of the Panasonic camera suggests it may have suffered failure of its Firewire chip. We see this frequently at the repair shop where I work - Firewire chips in cameras are prone to damage from ESD (ElectroStatic Discharge), otherwise known as getting zapped...

If possible try it on a third computer as confirmation, if that is the cause it's a moderately expensive repair.