I had a couple of Categories folders in my Stacks grid and deleted the folders prior to removing their respective icons from Stacks. Now they still show up in Stacks as blank icons and I cannot remove them. When I try to drag them out of Stacks to get rid of them, my Springboard locks up and goes into Safe Mode. I tried uninstalling and then reinstalling Stacks, but when I do that, the icons are still there. Any thoughts??