1. Install Compbiz Configuration Settings Manager.
( sudo apt-get install compizconfig-settings-manager )
2. Under the Desktop Section, click the Ubuntu Unity Plugin.
3. Disable the ALT key to show the HUD (It's the very first setting.) - You can set this to one of the other three key options if you'd like.
That should take care of the problem until Canonical or Linden Lab breaks it again.