Hi, have you tryed uninstall DE, DB and deleted the WinFileCache.dat too? (If you using Windows)
I see you say you have "I also have Design Extender and CSS Sculptor installed."
CSS Sculptor is included in Design Extender so no need to have the singel CSS Sculptor-extention installed.
If the case is that you have the CSS Sculptor installed that maybe cause the problem for you.
Try reinstall the 3 packs, Cart -> DE -> DB