I have a 1 TB WD external hard drive I store my music and videos on. I have noticed that the hard drive will randomly eject itself causing me to have to turn the external hard drive off and back on for the iMac to mount it again. I have a new iMac i5 and had a 24" 2.4 GHz iMac previously. I was using the firewire port on my previous iMac before and would occasionally experience this problem. However, having to use the USB port on the new iMac it is occurring on a daily basis. I have tried different ports on the back of the iMac thinking it was a USB problem, but that didn't seem to help. I have run disk utility and it says the drive is in good health. Any ideas? Thanks.