External HD Grinds or Clunks on Disk Access


Hoping to find out why a Maxtor Firewire external 40 Gig HD is making a clunking noise when some applications access the drive. It seems to happen most often when Classic applications access the drive while running 10.1. I don't seem to have the problem when booted in 9.1. The clunk lasts for just a second but it scares me a bit none the less as it is my primary back up drive. The drive is connected to my Pismo 400 via a Firewire port. Any comments would be appreciated.