Could not empty trash on my Mac OSX 10.6.8 Snow Leopard. Kept getting the error:
No matter which keys I hit while empty trash (shift, ctl, option, cmd).
This MacWorld article contained the clue that helped me.
DIY Terminal tricks
However, all those utilities merely send OS X commands that you can issue yourself in Terminal. To do so, first open Terminal (in /Applications/Utilities). Type
cd ~/.Trash and press Return. Then, type
sudo rm -R followed by a space (don’t leave out the space character—it’s essential). Don’t press Return yet.
Next, click the Trash icon in your Dock to open a window displaying the contents of the Trash. Select everything in that window and drag it into the Terminal window; this action adds the paths of all those files and folders to the
rm(remove) command. Now, press Return and enter your administrator password when prompted. In a moment or two (depending on how much was in your Trash), the Trash icon should return to its empty state.