Fix a problem with NX on Ubuntu 10.10 with the key d (inadvertently minimizing the current window)

Go to System → Preferences → Keyboard Shortcuts and set the shortcut for Hide all normal windows and set focus to desktop to something sane like Alt + D

update 2011-07-13: This happened again when I used Ubuntu 11.04 inside a NX session on a Mac OS X host computer. :(