I don't know if this is hardware or software based but when I am on my computer (the 24" iMac) and I choose 'File' or an App or 'Save' I get the beach ball and I look and my external HDDs are "working" ie. the lights are blinking and I hear them spin up. It actually happens kinda randomly. I wasn't accessing them! I have a 10-15 second delay in whatever I'm doing while the system checks, spins, or whatevers with the HDDs. WTH? The drives were plugged in and I formatted them to OS Journaled when I got them. What can I do to get the system to leave them alone when I'm not asking to access them!?!? Thanks guys!