There were many problems reported elsewhere with external devices like firewire drives and OSX Panther. Looks like not all have been fixed even by today's update to Panther, judging by the Macintouch reports reports

davideves, any chance the manufacturer has updated drivers on their website or there are settings which allow your external drive to "sleep"?

I know Macs usually just 'work', but looks like you have something unusual going on.

Sam--I noticed you've added jum's patch for the extra backup of fileurns.cache. Will that be in the next beta?