Ok, try it with sudo. It will ask you to type in your password after you run it. If it runs without anything happening except that you get a new prompt, then it is done and I guess didn't need to be run. That's what happened when I did it just now. It does look like there is a package that has not completed. Be sure that the Update program is closed before you do this.
Code:
sudo dpkg --configure -a
Another command that I've used before is:
Code:
sudo apt-get --fix-broken