That doesn't make sense to me, I'm denying my user name premission to read and write to the thumbcache files. I did it anyway, and Windows started to glitch out with trying to load thumbnails. It would load half of the pictures etc and then just stall out trying to load the rest. Figuring it was something to do with the premissions I changed, I reverted the change and now as soon as I leave the folders and go back to it. Windows has to load up new thumbnails, each time. This doesn't seem to effect the drives themselves, only the folders in them.
EDIT: Based on your idea, I went ahead and checked the premissions for the folders on the drives. Turns out, my user was not allowed to modify or have full acess. I enabled that to see what happens. For the time being, it's keeping the cached thumbnails. Will report back in a couple days, if it sticks for more than a day.