I don't know of any way to turn it off but it is actually a feature... after transferring books onto the reader, when it powers up, it indexes its contents so that it's ready to read and also this shows that the files and memory are OK... if it was disabled then I think most people would be rather tee'd off when away from their computer, to turn the reader on and have to wait for the indexing as well as being really annoyed if it failed to power up properly due to a problem file...
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