Quote - Do you have the hard drives set to turn off after an interval.

I do, but I don't think this is a spin-up issue, for it would happen much earlier (HD sleep time is 30 minutes). Also, once the drive has spun up again one would assume any further thumbnails should appear instantly as before, which I don't think they do.

I'd need to check more closely; As I said it's a minor annoyance, so I never bothered exploring it. For the time being let's say it might indeed be a spin-up issue.