title: Getting message "sudo: must be setuid root", but sudo IS already owned by root
body: <p>I'm trying to run sudo, and it's failing:</p>
  
  <pre><code>gregd@david $ sudo ls
  sudo: must be setuid root
  gregd@david $ which sudo
  /usr/bin/sudo
  gregd@david $ ll /usr/bin/sudo
  -rwxr-xr-x 1 root root 165K 2012-05-16 00:25 /usr/bin/sudo*
  </code></pre>
  
  <p>Any suggestions on how to fix this?</p>