Welcome to the wonderful wiggly world of system unsupported hacking! I have identical installs of Duality and other system components/versions on both my laptop and desktop - the lapop will switch without problems, but the deskop install of Duality has always given me problems (no number of reinstalls or troubleshooting has ever helped)... however, I am able to force-quit Duality once it hangs and relaunch the Finder manually and the switch has actually gone through every time (subsequent Aqua restores still run no problem). Try force-quitting Duality once it hangs, then force-quit the finder to see if the changes have actually taken effect or not... this always works for me