Alan, I suspect that we would need more info about your G4. Here is a link to a site called Mac Lookup. You put in the last three digits of your machine's serial number and they give you a tremendous amount of detailed information about your Mac. Check it out. http://www.everymac.com/ My question would whether or not your USB ports are USB2 or USB 1.1. Next I would ask if you had left at least 10% free space on all your drives. I normally give my drives even more breathing room with 20%. Otherwise jammed up drives will slow your machine to a crawl. Music files can clog a machine very quickly. Bill