You should also check to make sure the quickfinder option is turned off. MyComputer->right click external drive->properties->quickfinder tab and set search to normal. Otherwise it may be pulling in the find index and that is causing it to spin up. Either my externals don't go idle or I don't have the problem because I don't use the indexed search. In any case I don't notice a delay. It also could be that diskkeeper screws around with them enough that they never go idle.