Thanks Richard but I strongly suspect that the error will simply be that the drive didn't wake up (maybe it was in sleep mode or something). I'm not too concerned about the drive as I can easily switch it through a power-up cycle. I'm more concerned about getting my icons back.
Some further information.... in 'My Computer' I can see the drive OK and all it's contents (once it's back on line) but the desktop and taskbar icons seem to be lost forever. I've even tried deleting my desktop shortcuts and unpinning my taskbar items, then setting everything back up again but even that doesn't work.
So far, the only solution I've managed to find is to install some new software, which is very inconvenient.
[Edit...] I had an idea. Put the relevant icons somewhere on my C: drive then point my shortcuts to the icons. Since they're on my C: drive I should be able to see them, even if the E: drive goes offline occasionally. This is simple to do for a desktop shortcut (because you can specifically set its icon) but I can't find a way to do this for a Taskbar item. Any ideas??