Western Digital’s esata My Book has a serious design flaw, although don’t expect the company to admit it any time soon.
It “goes to sleep” after around 10 minutes, and there is little you can do to wake it up. If Final Cut is open it crashes the program. Meanwhile if you try to open Final Cut while My Book is in sleep mode you will find that the computer locks up, and if you dare to switch off the drive your program opens with all the video shown as offline.
Even when you eventually restart everything often the program opens with all those images still offline, and I am not sure of a quick fix to get them all back again, apart from dealing with each image one by one.
Western Digital need a good spanking for putting a defective device on the market. I guess they think testing their products is simply a task too far.
P.S. I asked the company for advice on curing the problem and they told me to download a file, which proved about as effective as their customer support… i.e. extremely poor.