we have two WD My Passport 320GB hard drives that both have the same issue. We use them as backup drives for our HP ML350 server with Small Business Server 2008. They have been upgraded to the latest firmare and the software removed.
Occasionally when they are swapped over the appear as USB not recognised. At first i thought it was the cable into the HDD as it seems very loose but i now look out for that. It seems to happen randomly and can normally be fixed by plugging the drive into the front usb if it was in the back or vice versa.
Why is this problem happening? Is it power issues? BIOS/Mothboard issue? Cable issue?
My next thought is to glue the cable into the external hard drive so i know its not an issue with that coming loose.
Thanks in advance