I've been thinking about this for 2 days man, lol... I hate being bothered like that. :D I know this sounds like it's coming from way out in left field, but humor me for a bit, at least so I can sleep tonight?
From the video, it looks to me like your cpu isn't running at full speed. Before it looked like your drives were spun down, but we removed that possibility when we set them to power off "never". Now while I doubt that your cpu isn't running slower than it should be, what's bugging me is that it's reacting as if it is. My thinking is that Speedstep is getting in your way.
So... to test my theory out... upon initial boot up we know that it takes forever and a day to access a drive; however, after that first initial wait period, does it also take just as long each time you access a drive/folder/file? For instance, if you click on Computer, wait for it, see Computer, then close Computer out, then immediately click Computer again, would it also take just as long? If not, what would happen if you waited 1 minute to click Computer again? How bout 15 minutes (given the default setting is 20 minutes)?
If (and this is the left field part) you can immediately access Computer with no wait on the second attempt, then that tells me (with my limited knowledge) that we're talking about a sleepy cpu (so to speak). It "works fine" switching users because switching users is cpu intensive... at least to the degree that it halts Speedstep.
There are a couple different things I'd like to try; although, I'm not quite sure in which order? First, I'd like to, in your bios' Advanced tab, set C1E Support to disable. Then, in the Vista Control Panel/System and Maintanence/Power Options/Change advanced power settings/processor power managment... set both fields to 100%.
We can change all that back later, but for now, I'm curious what would happen should you remove the Speedstep constraints?